u^^^^^ U.S. DEPARTMENT OF COMMERCE / Environmental Science Services Administration HANDBOOK NO. 1 - FACSIMILE PRODUCTS OFFICE OF METEOROLOGICAL OPERATIONS SILVER SPRING, MD. U.S. DEPARTMENT OF COMMERCE ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION WEATHER BUREAU SILVER SPRING, MD. 20910 December 29, 1967 IN REPLY REFER TO: Will TO All Recipients of "Weather Bureau Forecasters Handbook No. 1 - Facsimile Products" FROM : Director, Weather Bureau SUBJECT: Transmittal Memorandum for "Weather Bureau Forecasters Handbook No. 1 - Facsimile Products" Issuance 67-1 1. Material Transmitted: • First issuance under the new Weather Bureau Directives System of "WBFH No. 1 - Facsimile Products" (310 pages). 2. Summary ; This Handbook is the first in the series of Handbooks which will deal with the derivation of weather forecasts, 3. Effect on Other Instructions: "WBFH No. 1 -» Facsimile Products" replaces the draft copy of the Handbook distributed in June 1966. The binder and tabs issued with the draft copy may be used in assembling this version. Due to additions, however, there will be no tabs for sections SA-2A, SA-6, SA-7, SA~8, UA-3A, UA-7, SP~1A, UP-8A, UP-10A, UP-16, UP~17 UP«->18, and NA-1A. They may be provided at a later date depending on planned revisions. Additionally, the index section has been simplified to consist only of the annotated facsimile schedules. yrJli^uytQ . C umiu <^\ George P. Cressman S *TES O* + U.S. DEPARTMENT OF COMMERCE Alexander B. Trowbridge, Secretary ENVIRONMENTAL SCIENCE SERVICES ADMINISTRATION Robert M. White, Administrator WEATHER BUREAU George P. Cressman, Director WEATHER BUREAU FORECASTERS HANDBOOK NO. 1 FACSIMILE PRODUCTS OFFICE OF METEOROLOGICAL OPERATIONS SILVER SPRING, MD. FEBRUARY 1968 111 WEATHER BUREAU FORECASTERS HANDBOOK NO 1 - FACSIMILE PRODUCTS RECORD OF CHANGES Change No. /Date eh- 5 Date Entered IV Entered By L WBFH NO. ^ ISSUANCE A7.) JO-J-67 INTRODUCTION It has been said with some truth that meteorology is a science without a technology and that weather forecasting is presently an art rather than a science. Both of these characterizations describe the failure of our pro- fession to achieve a state of organization in our scientific knowledge that will permit its systematic application to the generation of products and services required by current demand. The organization and ordering of scientific knowledge for specific applica- tion is the goal of applied research. It is only within about the last decade that we have seen the initiation of research efforts aimed specifical- ly at weather forecasting on a scale which the complexity and importance of the problem demand. Much progress has been made, particularly, in the devel- opment of mathematical models that reproduce rather well the gross features of atmospheric motions for periods of one or two days. But we have achieved only the crudest kinds of physical and statistical formulations of the weather forecast problem involving such elements as cloudiness, precipitation, tem- perature, and wind flow near the ground. In spite of the fact that we do not have satisfactory techniques and methods for systematically deriving weather forecasts, it is essential that we set down in one place, in the proper form, what we do know about methods for making various kinds of forecasts. It is for this purpose that the original Forecasters Handbook was designed. Recently, however, the Weather Bureau implemented a new Directives System. In this new System, the various technical instructions issued by the Weather Bureau will be called "handbooks". Thus, "Weather Bureau Forecasters Handbook Number 1 - Facsimile Products" is the first in the series of handbooks that will provide information and instruction in the derivation of weather fore- casts. Specifically, "WBFH No. 1 - Facsimile Products" provides background information on the production of facsimile charts transmitted on the National, Weather Bureau Forecast Center, Honolulu, and High Altitude Facsimile Circuits. (Information on the charts transmitted on the Intra-Alaska Circuit will be added later.) To use this Handbook one begins with one of the annotated fax schedules, ob- tains the Handbook number of the chart of interest and turns to the corre- spondingly labeled green tab. Usually only brief discussions and descrip- tions of the charts are provided, but references to more detailed information are frequently given. It is planned to update the contents of the "Forecasters Handbook" series quarterly beginning with January. The compilation of material included in this Handbook has involved the ideas and labors of a number of individuals and organizations of the Weather Bureau. Space does not permit the listing of all who helped in the preparation of the contents. However, without the participation of Mr. Edwin B. Fawcett of WBFH NO. 1 ISSUANCE 67-1 JO-J-67 the Analysis and Forecast Division of National Meteorological Center who supplied most of the technical descriptions of the NMC products, Julius Badner and Matthew H. Kulawiec of Technical Procedures Branch, Weather Analysis and Prediction Division, who prepared the final and original versions of the write-ups, this document could never have been developed. Technical editing and final organization were accomplished by Philip A. Calabrese of Technical Procedures Branch, Weather Analysis and Prediction Division WBFH NO. ? ISSUANCE 67-1 10-1-67 VI WEATHER BUREAU FORECASTERS HANDBOOK NO . 1 - FACSIMILE PRODUCTS TABLE OF CONTENTS INTRODUCTION V SELECTED ABBREVIATIONS viii 1 . INDEX AND FACSIMILE SCHEDULES 1-1 NATIONAL FACSIMILE SCHEDULE 1-1 HIGH ALTITUDE FACSIMILE SCHEDULE 1-2 PACIFIC/ CONTINENTAL FACSIMILE SCHEDULE 1-3 ATLANTIC/ CONTINENTAL FACSIMILE SCHEDULE 1-4 GULF /CONTINENTAL FACSIMILE SCHEDULE 1-5 SOUTH ATLANTIC COASTAL FACSIMILE SCHEDULE 1-6 HONOLULU RADIO FACSIMILE SCHEDULE 1-7 2. SA 1-8 SURFACE ANALYSES 2-1 3. UA 1-7 UPPER-AIR ANALYSES 3-1 4. AC 1-7 AUXILIARY ANALYSES 4-1 5. SP 1-10 SURFACE PROGNOSES 5-1 6. UP 1-18 UPPER-AIR PROGNOSES 6-1 7. E 1-5 EXTENDED FORECAST CHARTS 7-1 8. NA 1-2 NEPHANALYSES 8-1 9. APPENDICES 1-55 9-1 V13 WBFH NO. J ISSUANCE 67-1 7 0-1-67 SELECTED ABBREVIATIONS A&FD AIREP AIRINC ARTC AW BAMS CAT CDC CRT FNWF ITC NAWAC NESC NMC NWP PE PEP PIBAL PI RE PS RADAT RADU RAOB RAWARC RAWIN SELS SLYH TAFORS TOE WBAS Analysis and Forecast Division, NMC Air-Report Aeronautical Radio Incorporated Air Route Traffic Control Airway Weather Bulletin of the American Meteorological Society Clear Air Turbulence Control Data Corporation Cathode Ray Tube Fleet Numerical Weather Facility Intertropical Convergence Zone National Weather Analysis Center (Now NMC) National Environmental Satellite Center National Meteorological Center Numerical Weather Prediction Primitive Equation Primitive Equation Precipitation Pilot Balloon Pilot Reports Radar Data Radar Unit Radiosonde Observation Radar Warning Circuit Rawinsonde Severe Local Storms Sanders, LaRue , Younkin, Hovermale Terminal Airport Forecasts Top of Ekman (layer) Weather Bureau Airport Station Vlll NATIONAL FACSIMILE SCHEDULE Circuit WFX 1234 GMT FAX HAND- FROM Chart Description TIME GMT FAX HAND- FROM Chart Description TIME NO. BOOK NO. OR V.T. GMT NO. BOOK NO. OR V.T. GMT 0002 1 WBC Extended Forecast Charts 12 1145 58 UA-4 WBC Analysis 500 mb 00 E-2,3 Forecast 5 day (Mon-Wed-Fri) 1200 60 SP-9 MKC Prog severe wx outlook (12Z-12Z) E-4 Prog sfc 72 hr (Sun-Tue-Thu-Sat) 1210 61 SP-6 WBC Prog QPF guidance and NA-2 Ice Chart* SP-7 WBC Prog heavy snow E-5 30-dav Outlook (1st & 15th) 1220 62 SP-8 WBC Forecasts temperature change 0042 2 NA-1A WBC Satellite Cloud Chart 1230 63 WBC Genot Ern US to Wrn Atl (Mosaic) 1240 64 NA-1 WBC Analysis nephanalysis 0050 3 SA-5 MKC Ana 1 sis radar summary 00 1250 65 SA-5 MKC Analysis radar summary 12 0102 4 UP-4 WBC Prog 500 mb 72 hr 12 1302 66 UP-4 WBC Prog 500 mb 72 hr 00 0114 5 AC-6 WBC Data snow cover/snowfall 00 1314 67 AC-6 WBC Data snow cover 12 0122 6 AC-4 WBC Data maximum temperatures 00 1322 68 AC-4 WBC Data minimum temperatures 12 0132 7 SA-1 WBC Analysis surface 6 hrly 00 1332 69 SA-1 WBC Analysis surface 6 hrlv 12 0207 8 UA-1 WBC Analysis 500 mb 00 1407 70 UA-1 WBC Analysis 500 mb 12 0219 9 SA-4 WBC Analysis weather depiction 01 1419 71 SA-4 WBC Analysis weather depiction 13 0237 10 UA-1 WBC Analysis 850 mb 00 1437 72 UA-1 WBC Analysis 850 mb 12 AC-1 WBC Analysis pressure change 12 hr AC-1 WBC Analysis pressure change 12 hr 0247 11 UP-1 WBC Analysis vort+500 mb initial Progs brtrpc 12 hr, 24 hr, 36 hr 1447 73 UP-1 WBC Analysis vort + 500 mb, initial Progs brtrpc 12 hr, 24 hr, 36 hr 0302 12 SP-4 WBC Prog surface, elds, + precip 12 hr Prog sig weather low lvl 24 hr 12 00 1502 74 SP-4 WBC Prog surface, elds + precip 12 hr Prog sig weather low lvl 24 hr 00 12 0312 13 AC- 7 WBC Data winds aloft - lower lvls 00 1512 75 AC-7 WBC Data winds aloft - lower lvls 12 0322 14 AC-7 WBC Data winds aloft - intmdt lvls 00 1522 76 AC-7 WBC Data winds aloft - intmdt lvls 12 0332 15 AC-7 WBC Data winds aloft - upper lvls 00 1532 77 AC-5 WBC Data rainfall 24 hr 12 Data tropopause 1542 78 AC-7 WBC Data winds aloft - upper lvls 12 0342 16 UA-1 WBC Analysis 700 mb 00 Data tropopause 0352 17 SA-5 MKC Analysis radar summary 03 1552 79 UA-1 WBC Analysis 700 mb 12 0404 18 AC- 3 WBC Analysis stability + precip water 00 1602 80 SA-5 MKC Analysis radar summary 15 Freezing level - rel humidity 1614 81 AC- 3 WBC Analysis stability + precip water 12 0414 19 UP-10 WBC Prog Trop max wind and wind shear 12 Freezing level - rel humidity UP-11 WBC Prog sig weather 1624 82 UP-10 WBC Prog trop max wind and wind shear 00 0424 20 NA-1A WBC Satellite Cloud Chart UP-11 WBC Prog sig weather Wrn Pac to Wrn Atl (Mosaic) 1634 83 SA-1 WBC Analysis surface 3 hrly 15 0434 21 SA-1 WBC Analysis surface 3 hrly 03 1654 84 SA-3 WBC Analysis surface 6 hrly 12 0454 22 SA-3 WBC Analysis surface 6 hrly 00 with 1000-500 mb thickness with 1000-500 mb thickness 1706 85 SA-4 WBC Analysis weather depiction 16 0506 23 SA-4 WBC Analysis weather depiction 04 1724 86 UA-6 WBC Analysis maximum wind 12 0524 24 UA-6 WBC Analysis maximum wind 00 Analysis wind shear Analysis wind shear 1734 87 UA-1 WBC Analysis 300 mb 12 0534 25 UA-1 WBC Analysis 300 mb 00 1744 88 UA-1 WBC Analysis 200 mb 12 0544 26 UA-1 WBC Analysis 200 mb 00 1754 89 UA-2 WBC Analysis 500 mb 12 0554 27 SA-5 MKC Analysis radar summary 05 1806 91 Circuit lineup (1806-1842Z) 0600 31 UA-2 WBC Analysis 500 mo 00 1842 92 SA-5 MKC Analysis radar summary 18 0612 32 NA-1 WBC Analysis nephanalysis (10 min) 1854 93 UA-2 WBC Analysis 300 mb 12 0622 33 NA-1 WBC Analysis nephanalysis (16 min) 1904 94 UP-4 WBC Prog 500 mb 36 hr 00 0638 34 UA-2 WBC Analysis 300 mb 00 1916 95 UP-4 WBC Prog 500 mb 24 hr, 48 hr 12 0648 35 SA-5 MKC Analysis radar summary 06 1926 96 UP- 2 WBC Analysis vert vel + 500 mb initial 0700 36 UP-4 WBC Prog 500 mb 36 hr 12 Prog brclnc 12 hr, 24 hr, 36 hr 0712 37 UP-4 WBC Prog 500 mb 24 hr , 48 hr 00 1941 97 SA-3 WBC Analysis surface 6 hrly 18 0722 38 UP- 2 WBC Analysis vert vel + 500 mb initial 2016 98 SA-4 WBC Analysis weather depiction 19 Progs brclnc 12 hr, 24 hr, 36 hr 2034 99 AC-1 WBC Analysis pressure change 12 hr 0737 39 SA-3 WBC Analysis surface 6 hrly 06 SP-6 WBC Prog QPF guidance and 0812 40 SA-4 WBC Analysis weather depiction 07 SP-7 WBC Prog heavy snow 0830 41 SP-6 WBC Prog QPF guidance and 2044 100 SP-3 WBC Prog sfc, elds + precip 24 hr 48 ir 12 SP-7 WBC Prog heavy snow 2054 101 SA-5 MKC Analysis radar summary (6 min) 20 AC-1 WBC Analysis pressure change 12 hr 2100 102 AC-7 WBC Data winds aloft - intmdt lvls 18 0840 42 SP-3 WBC Prog sfc, elds + precip 24 hr 48 hr 00 2110 103 AC-7 WBC Data winds aloft - lower lvls 18 0850 43 SA-5 MKC Analysis radar summary (6 min) 08 2120 104 UP-4 WBC Prog 300 mb 24 hr 12 0900 44 AC-7 WBC Data winds aloft - intmdt lvls 06 200 mb 24 hr 12 0910 45 AC-7 WBC Data winds aloft - lower lvls 06 2130 105 UP-4 WBC Prog 850 mb 24 hr 12 0920 46 UP-4 WBC Prog 300 mb 24 hr 00 700 mb 24 hr 12 200 mb 24 hr 2140 106 AC-6 WBC Data snowfall 6 hrly 0930 47 UP-4 WBC Prog 850 mb 24 hr 00 AC-7 WBC Data winds aloft - upper lvls 18 700 mb 24 hr 2150 107 SA-5 MKC Analysis radar summary 21 0940 48 AC-6 WBC Data snowfall 6 hrly 2202 108 UP-10 WBC Prog trop max wind and wind shear 06 AC-7 WBC Data winds aloft - upper lvls 06 UP-11 WBC Prog sig weather 0950 49 SA-5 MKC Analysis radar summary 09 2212 109 UP-4 WBC Prog 700 mb 36 hr 00 1002 50 UP-10 UP-11 WBC WBC Prog trop max wind and wind shear Prog sig weather 18 2222 110 SP-4 WBC Prog surface, elds + precip 12 hr Prog sig weather low level 24 hr 06 18 1012 51 UP-4 WBC Prog 700 mb 36 hr 12 2232 111 SA-1 WBC Analysis surface 3 hrly 21 1022 52 SP-4 WBC Prog surface, elds + precip 12-hr 18 2252 112 SA-5 MKC Analysis radar summary 22 Prog sig weather low lvl 24-hr 06 2258 113 SP-2 WBC Prog surface, precip 30 hr 00 1032 53 SA-1 WBC Analysis surface 3 hrly 09 Prog 1000-500 thickness 36 hr 1052 54 SP-2 WBC Prog surface, precip 30 hr 12 2308 114 UP-4 WBC Prog 300 mb 36 hr 00 Prog 1000-500 mb thickness 36 hr 2318 115 SA-4 WBC Analysis weather depiction 22 1102 55 UP-4 WBC Prog 300 mb 36 hr 12 2336 116 NA-1 WBC Analysis nephanalysis 1112 56 SA-4 WBC Analysis weather depiction 10 2346 117 SP-7 WBC Prog heavy snow 1130 57 SA-5 MKC Analysis radar summary 11 SP-8 WBC Forecasts temperature change 2356 118 SA-5 MKC Analysis radar summary 23 *Sent f ollowing the 72-hr surface prog on Sunday, Tuesday, or Thursday Only Chart will not be sent whe n 1st or 15th falls on these days. 1-1 V/BFH NO. I 671 ISSUANCE 10-1-67 HIGH ALTITUDE FACSIMILE SCHEDULE Circuit GF 10200 GMT FAX HAND- FROM Chart Description TIME GMT FAX HAND- FROM Chart Description TIME NO. BOOK NO. OR V.T. GMT NO. BOOK NO. OR V.T. GMT 0004 301 1204 355 NA-1A WBC Data satellite 0010 302 UP- 13 SFO Progs composite 700 & 500 mb 12 North Pacific (Mosaic) 0020 303 UP-13 SFO Progs composite 300, 200 mb 1214 356 UP-13 SFO Progs composite 700 & 300 mb 00 & sig weather (sfc-150 mb) 12 1224 357 UP-13 SFO Progs composite 300, 200 mb 0031 304 UP-5 WBC Prog 500 mb 30 hr 18 & sig weather (sfc-150 mb) 00 0041 305 UP-5 WBC Prog 300 mb 30 hr 18 1235 358 UP-5 WBC Prog 500 mb 30 hr 06 0051 306 UP-5 WBC Prog 200 mb 30 hr 18 1245 359 UP-5 WBC Prog 300 mb 30 hr 06 0101 307 UP-5 WBC Prog 700 mb 30 hr 18 1255 360 UP-5 WBC Prog 200 mb 30 hr 06 0111 308 UP-15 MIA Prog sig weather (503-150 mb) 12 1305 361 UP-5 WBC Prog 700 mb 30 hr 06 0121 309 UP- 15 MTA Prog 300 mb 12 1315 362 UP-15 MIA Prog sig weather (500-150 mb) 00 0131 310 UP-15 MIA Prog 200 mb 12 1325 363 UP-15 MIA Prog 300 mb 00 0141 311 UP-15 MIA Prog 500 mb 12 1335 364 UP-15 MIA Prog 200 mb 00 0151 312 NA-1A WBC Data satellite Wm No America-NE Pac (Mosaic) 1345 365 UP-15 1355 366 MIA Prog 500 mb 00 0201 313 UO Prog sig weather (400-150 mb) 12 1401 367 UO Prog sig weather (400-150 mb) 00 0211 314 UP-14 JFK Prog sig weather (700-150 mb) 12 1411 368 UP-4 JFK Prog sig weather (700-150 mb) 00 0219 315 UP-11 WBC Prog sig weather (400-150 mb) 12 1419 369 UP-11 WBC Prog sig weather (400-150 mb) 00 0227 316 UP- 12 ANC Prog sig weather (700-150 mb) 12 1427 370 UP-12 ANC Prog sig weather (700-150 mb) 00 0234 317 UP-5 WBC Prog 700 mb 24 hr 12 1434 371 UP-9 WBC Prog 700 mb 24 hr 00 0300 318 SA-2 WBC Analysis preliminary surface 00 1500 372 SA-2 WBC Analysis preliminary surface 12 0320 319 1520 373 NA-1A WBC Data satellite 0335 320 NA-1A WBC Data satellite European Northeastern Asia (Mosaic) East equatorial Pacific (Mosaic ) 1530 374 WBC Genot 0350 321 NA-1A WBC Data satellite 1540 375 SP-2 WBC Prog surface 30 hr 06 United States (Mosaic) 1606 376 UA-3 WBC Analysis 500 mb 12 0400 322 UA-3 WBC Analysis 500 mb 00 1626 377 Circuit lineup 0420 323 SP-1 WBC Prog surface 30 hr 18 1725 378 UP-13 SFO Progs composite 700 & 500 mb 05 0446 324 UP-13 SFO Progs composite 700 & 500 mb 18 1735 379 UP-13 SFO Progs composite 300, 200 mb 0456 325 UP- 13 SFO Progs composite 300, 200 mb & sig weather (sfc-150 mb) 06 & sig weather (sfc-150 mb) 18 1746 380 UP-15 MIA Prog sig weather (500-150 mb) 05 0507 326 NA-1 WBC Data satellites' 1756 381 UP-15 MIA Prog 300 mb 05 0517 327 UA-3 WBC Analysis 300 mb 00 1806 382 UP-15 MIA Prog 200 mb 06 0524 328 Test period* 1816 383 UP-15 MIA Prog 500 mb 06 0536 329 UP-15 MIA Prog sig weather (500-150 mb) 18 1826 384 UA-1 WBC Analysis 300 mb 12 0546 330 UP-15 MIA Prog 300 mb 18 1833 385 UP-8A WBC Prog 500 mb & 24 hr vort 0556 331 UP-15 MIA Prog 200 mb 18 & 24 hr 700 mb vert vel 12 0606 332 UP-15 MIA Prog 500 mb 18 1843 386 UP-9 WBC Prog 300 mb 18 hr 06 0616 333 NA-1A WBC Data satellite 1909 387 UP-10A WBC Prog trop vert wind shear 18 hr 06 South Pacific (Mosaic) 1935 388 UP-9 WBC Prog 500 mb 18 hr 06 0626 334 2001 389 UP-9 WBC Prog 700 mb 18 hr 06 0633 335 UP-8A WBC Prog 500 mb & 24 hr vort 2027 390 UO Prog sig weather (400-150 mb) 06 & 24 hr 700 mb vert vel 00 2037 391 UP-14 JFK Prog sig weather (700-150 mb) 06 0643 336 UP-9 WBC Prog 300 mb 18 hr 18 2045 392 UP-11 WBC Prog sig weather (400-150 mb) 06 0709 337 UP-10A WBC Prog trop-vert wind shear 18 hr 18 2053 393 UP-12 ANC Prog sig weather (700-150 mb) 06 0735 338 UP-9 WBC Prog 500 mb 18 hr 18 2100 394 SA-2 WBC Analysis preliminary surface 18 0801 339 UP-9 WBC Prog 700 mb 18 hr 18 2120 395 UP-9 WBC Prog 700 mb 24 hr 12 0827 340 UO Prog sig weather (400-150 mb) 18 2130 396 UP-5 WBC Prog 200 mb 24 hr 12 0837 341 UP-14 JFK Prog sig weather (700-150 mb) 18 2140 397 NA-1A WBC Data satellite 0845 342 UP-11 WBC Prog sig weather (400-150 mb) 18 Arctic North Pole (Mosaic) 0853 343 UP-12 ANC Prog sig weather (700-150 mb) 18 2150 398 UP-16 HNL Progs composite 300 & 200 mb 12 0900 344 SA-2 WBC Analysis preliminary surface 06 2210 399 0920 345 UP-9 WBC Prog 700 mb 00 2212 400 UP-16 HNL Prog composite 500 mb & sig 0930 346 UP-5 WEC Prog 200 mb 24 hr 00 weather (sfc-150 mb) 12 0940 347 NA-1A WBC Data satellite 2221 401 UP-9 WBC Prog 300 mb 24 hr 12 North Pacific (Mosaic) 2247 402 UP-10A WBC Prog trop vert wind shear 24 hr 12 0950 348 UP- 16 HNL Progs composite 300 & 200 mb 00 2312 403 UP-9 WBC Prog 500 mb 24 hr 12 1010 1012 349 350 UP-16 HNL Progs composite 500 mb & sig 2338 404 SP-1 WBC Prog surface 24 hr 12 ' weather (sfc-150 mb) 00 NOTES: #Data as available to meet requirements. 1021 351 UP-9 WBC Prog 300 mb 24 hr 00 Times of data, areas of coverage, map pro- jections, etc., variable. 1047 352 UP-10A WBC Prog trop-vert wind shear 24 hr 00 1112 353 UP-9 WBC Prog 500 mb 24 hr 00' 1138 354 SP-1 WBC Prog surface 24 hr 00 *ANC TEST ON WBC TEST ON SUNDAY MONDAY JFK TEST ON TUESDAY MIA TEST ON WEDNESDAY SFO TEST ON THURSDAY WWV TEST ON FRIDAY (TIME SIGNAL) UO TEST ON SATURDAY 1-2 WBFH NO. J ISSUANCE 67-1 10-1-67 PACIFIC/CONTINENTAL FACSIMILE SCHEDULE Circuit GF 10206 GMT FAX HAND- Chart Description TIME GMT FAX HAND- Chart Description TIME NO. BOOK NO. OR V.T. GMT NO. BOOK NO. OR V.T. GMT 0000 900 E-l 5-Day Observed 1200 950 NA-1A Satellite Cloud Chart 170E-130W (Mo saic) 0010 901 1220 950A NA-1 Analysis nephanalysis 0025 902 NA-1A Satellite Cloud Chart 60W-120W (Mosaic) 1240 951 Genot 0045 902A NA-1A Satellite Cloud Chart Ern Pac-Wrn U.S. (Mosaic) 1255 1300 952 953 Circuit lineup 0055 903 1400 954 0120 904 NA-1 Analysis nephanalysis 1415 955 AC- 5 Data prelim precip 24 hr 12 0140 905 1425 956 0220 906 1430 957 UA-1 Analysis 700 mb w/d 12 0230 907 UA-1 Analysis 700 mb w/d 00 1440 958 UA-5 Analysis surface 12 0240 908 UA-5 Analysis sfc and 1000-500 mb thickne ss 00 with 1000-500 mb thickness AC- 2 Analysis 500 mb height change 24 hr 00 1450 959 UA-1 Analysis 850 mb w/d 12 0250 909 UA-1 Analysis 850 mb w/d 00 1500 961 SA-2 Analysis preliminary surface 12 0300 911 SA-2 Analysis preliminary surface w/d 00 1520 962 0320 912 UA-3A Analysis 850 mb chart (no data) 00 1530 963 NA-1 Analysis nephanalysis 0340 913 NA-1 Analysis nephanalysis 1600 964 0400 914 1620 965 UA-5 Analysis 1000-500 mb thickness w/d 12 0420 915 UA-5 Analysis 1000-500 mb thickness w/d 00 1640 966 SA-1 Analysis surface 3 hrly (sectional) 15 0440 916 SA-1 Analysis surface 3 hrly (sectional) 03 1650 966A 0450 91 6A 1700 967 UA-3 Analysis 500 mb w/d 12 0500 917 UA-3 Analysis 500 mb w/d 00 1720 968 NA-1 Analysis nephanalysis 0520 918 1728 969 UA-3 Analysis 300 mb w/d 12 0528 919 UA-3 Analysis 300 mb w/d 00 1748 971 UA-3 Analysis 700 mb w/d 12 0548 921 UA-3 Analysis 700 mb w/d 00 1808 972 UA-3 Analysis 200 mb w/d 12 0608 922 UA-3 Analysis 200 mb w/d 00 1828 973 UP-4 Prog 500 mb baroclinic 12 hr 00 0628 923 UP-4 Prog 500 mb baroclinic 12 hr 12 1840 974 UA-2 Analysis initial 500 mb vorticity 12 0640 924 UA-2 Analysis initial 500 mb vorticity 00 1850 975 0650 925 1855 976 UP-4 Prog 300/200 mb 24 hr 12 0655 926 UP-4 Prog 300/200 mb 24 hr 00 1905 977 UP-8 Prog 500 mb vorticity 24 hr 12 0705 927 UP-8 Prog 500 mb vorticity 24 hr 00 1915 978 UP-4 Prog 700/850 mb 24 hr 12 0715 928 UP-4 Prog 700/850 mb 24 hr 00 1925 979 UP-5 Prog 300/500 mb 24 hr 12 0725 929 UP-5 Prog 300/500 mb 24 hr 00 1940 981 SP-1 Prog surface 24 hr 12 0740 931 SP-1 Prog surface 24 hr 00 1952 982 SP-1 Prog surface 36 hr 00 0752 932 SP-1 Prog surface 36 hr 12 2004 983 UP-4 Prog 500 mb 72 hr 00 0804 933 UP-4 Prog 500 mb 72 hr 00 2016 984 UP-3 Analysis initial 0816 934 UP-3 Analysis initial Prog 12, 18, 24 hr mean R. H. 2022 985 Prog 12, 18, 24 hr mean R.H. 0822 935 2030 986 SP-3 Prog surface Package B 0830 936 SP-3 SP-5 Prog surface Package A SP-5 SP-8 SP-8 2100 987 SA-2 Analysis preliminary surface w/d 18 0900 937 SA-2 Analysis preliminary surface w/d 06 2120 988 E-2 Extended forecast 5-day anomalies 0935 939 UP- 7 Analysis initial Prog 12, 24, 36 hr lifted index 2130 989 E-3 E-4 Progs 5-day Prog sfc extended forecast 72 hr 12 12 0950 941 2150 991 E-2 Prog sfc and 700 mb and 5 day mean 1000 942 2200 992 UP-7 Analysis initial 1010 943 Prog 12, 24, 36 hr lifted index 1020 944 2215 993 NA-1A Satellite Cloud Chart 1040 945 SA-1 Analysis surface 3 hrlv (sectional) 09 Ern US-Wrn Europe (Mosaic) 1050 94 5 A 2225 994 NA-1 A Satellite Cloud Chart 1100 946 UP- 6 Forecast Error Charts 500 mb 36 hr 12 Polar Centered 40N-60W (Mosaic) 1110 947 2245 995 SA-1 Analysis surface 3 hrlv (sectional) 21 1120 948 2255 995A 1140 949 2300 2310 996 997 UP-6 Forecast Error Charts 500 mb 36 hr 00 2320 998 NA-1 A Satellite Cloud Chart 20W-100W (Mosaic) 2340 999 NA-1 Analysis nephanalysis NOTES: 1. All transmissions from WBC. 2. Numbers 910, 920, 930, 940, 960, 970, 980, and 990 will not be used. 3. -j/d = with data. * 1-3 WBFH NO. 1 ISSUANCE 67-1 TO-t-67 ATLANTIC/CONTINENTAL FACSIMILE SCHEDULE Circuit GF 10207 GMT FAX HAND- Chart Description TIME GMT FAX HAND- Chart Description TIME NO. BOOK 3R NO. BOOK OR NO. V .T. NO. V ,T. GMT GMT 0000 800 E-l 5 day observed 1200 850 NA-1 A Satellite Cloud Chart 170E-130W (Mosaic ) 0010 801 1220 850A NA-1 Analysis nephanalysis 0025 802 NA-1A Satellite Cloud Chart 60W-120W (Mosaic) 1240 851 Genot 0045 802A NA-1A Satellite Cloud Chart Ern Pac-Wrn U. S. (Mosaic) 1255 1300 852 853 Circuit lineup 0055 803 1400 854 0120 804 NA-1 Analysis nephanalysis 1415 855 AC-5 Data prelim precip 24 hr 12 0140 805 1425 856 0220 806 1430 857 UA-1 Analysis 700 mb w/d 12 0230 807 UA-1 Analysis 700 mb w/d 00 1440 858 UA-5 Analysis sfc and 1000-500 mb thickness 12 0240 808 UA-5 Analysis sfc and 1000-500 mb thickness 00 AC-2 Analysis 500 mb height change 24 hr 12 AC-2 Analysis 500 mb height change 24 hr 00 1450 859 UA-1 Analysis 850 mb w/d 12 0250 809 UA-1 Analysis 850 mb w/d 00 1500 861 SA-2 Analysis preliminary surface w/d 12 0300 811 SA-2 Analysis preliminary surface w/d 00 1520 862 0320 812 1530 863 NA-1 Analysis nephanalysis 0340 813 NA-1 Analysis nephanalysis 1600 864 0400 814 1620 865 UA-5 Analysis 1000-500 mb thickness w/d 12 0420 815 UA-5 Analysis 1000-500 mb thickness w/d 00 1640 866 SA-1 Analysis surface 3 hrly (sectional) 15 0440 816 SA-1 Analysis surface 3 hrly (sectional) 03 1650 866A 0450 816A 1700 867 UA-3 Analysis 500 mb w/d 12 0500 817 UA-3 Analysis 500 mb w/d 00 1720 868 NA-1 Analysis nephanalysis 0520 818 1728 869 UA-3 Analysis 300 mb w/d (240 SPM) 12 0528 819 UA-3 Analysis 300 mb w/d (240 SPM) 00 1740 871 UA-3 Analysis 700 mb (240 SPM) 12 0540 821 UA-3 Analysis 700 mb (240 SPM) 00 1752 872 UA-3 Analysis 200 mb (240 SPM) 12 0552 822 UA-3 Analysis 200 mb (240 SPM) Q0 1818 873 UP-4 Prog 500 mb baroclinic 12 hr (240 SPM) 00 0618 823 UP-4 Prog 500 mb baroclinic 12 hr (240 SPM) 12 18^0 874 UA-2 Analysis initial 500 mb vort (240 SPM) 12 0630 824 UA-2 Analysis initial 500 mb vort (240 SPM) 00 1840 875 0640 825 1845 876 UP-4 Prog 300/200 mb 24 hr (240 SPM) 12 0645 826 UP-4 Prog 300/200 mb 24 hr (240 SPM) 00 1855 877 UP-8 Prog 500 mb vorticity 24 hr (240 SPM) 12 0655 827 UP-8 Prog 500 mb vorticity 24 hr (240 SPM) 00 1905 878 UP-4 Prog 700/850 mb 24 hr (240 SPM) 12 0705 828 UP-4 Prog 700/350 mb 24 hr (240 SPM) 00 1915 879 0715 829 1930 881 SP-1 Prog surface 24 hr (240 SPM) 12 0730 831 SP-1 Prog surface 24 hr (240 SPM) 00 1940 882 SP-1 Prog surface 36 hr (240 SPM) 00 0740 832 SP-1 Prog surface 36 hr (240 SPM) 12 1950 883 UP-4 Prog 500 mb 72 hr (240 SPM) 12 0750 833 UP-4 Prog 500 mb 72 hr (240 SPM) 00 2005 884 UP-3 Analysis initial 0805 834 UP- 3 Analysis initial Prog 12, 18, 24 hr mean R. H. (240 SPM) Prog 12, 18, 24 hr mean R. H. (240 SPM) 2030 886 SP-3 Prog surface Package B 0822 835 SP-5 0830 836 SP-3 Prog surface Package A SP-8 SP-5 2100 887 SA-2 Analysis preliminary surface w/d 18 SP-8 2120 888 E-2 Extended Forecast 5 day Anomalies 0900 837 SA-2 Analysis preliminary surface w/d 06 2130 889 E-3 Progs 5 day 12 0935 839 UP- 7 Analysis initial E-4 Prog sfc extended forecast 72 hr 12 Prog 12, 24, 36 hr lifted index 2150 891 E-2 Prog sfc and 700 mb 5 day mean 0950 841 2200 892 UP- 7 Analysis initial 1000 842 Prog 12, 24, 36 hr lifted index 1010 843 2215 893 NA-1A Satellite Cloud Cover 1020 844 Ern US-Wrn Europe (Mosaic) 1040 845 SA-1 Analysis surface 3 hrly (sectional) 09 2225 894 NA-1 A Satellite Cloud Cover 1050 845A Polar Centered 40N-60W (Mosaic) 1100 846 UP-6 Forecast Error Charts 500 mb 36 hr 12 2245 895 SA-1 Analysis surface 3 hrly (sectional) 21 1110 847 SP-10 Progs sea surface 12 hr, 36 hr 00 2255 895A 1120 848 2300 896 UP-6 Forecast Error Charts 500 mb 36 hr 00 1140 849 2310 897 SP-10 Progs sea surface 12 hr, 36 hr 12 2320 898 NA-1A Satellite Cloud Chart 20W-100W (Mosaic) 2340 899 NA-1 Analysis nephanalysis NOTES: 1. All transmissions from W3C. 2. Numbers 810, 820, 830, 840, 860, 870, 880, and 890 will not be used. 3. w/d = with data. J WBFH NO. 1 ISSUANCE 67-1 JO-J-67 1-4 GULF/CONTINENTAL FACSIMILE SCHEDULE Circuit GF 10208 GMT FAX HAND- Chart Description TIME GMT FAX HAND- Chart Description TIME NO. BOOK NO. OR V.T. GMT NO. BOOK NO. OR V.T. GMT 0000 800 E-l 5-Day Observed 1200 850 NA-1 A Satellite Cloud Chart 170E-130W (Mosaic) 0010 801 1220 850A NA-1 Analysis nephanalysis 0025 802 NA-1A Satellite Cloud Chart 60W-120W (Mosaic) 1240 851 Genot 0045 802A NA-1A Satellite Cloud Chart Ern Pac-Wrn U.S. (Mosaic) 1255 1300 852 853 Circuit lineup 0055 803 1400 854 0120 804 NA-1 Analysis nephanalysis 1415 855 AC-5 Data prelim precip 24 hr 12 0140 805 1425 856 0220 806 1430 857 UA-1 Analysis 700 mb w/d 12 0230 807 UA-1 Analysis 700 mb w/d 00 1440 858 UA-5 Analysis sfc and 1000-500 mb thickne ss 12 0240 808 UA-5 Analysis sfc and 1000-500 mb thickness 00 AC-2 Analysis 500 mb height change 24 hr 12 AC- 2 Analysis 500 mb height change 24 hr 00 1450 859 UA-1 Analysis 850 mb w/d 12 0250 809 UA-1 Analysis 850 mb w/d 00 1500 861 SA-2 Analysis preliminary surface w/d 12 0300 811 SA-2 Analysis preliminary surface w/d 00 1520 862 0320 812 1530 863 NA-1 Analysis nephanalysis 0340 813 NA-1 Analysis nephanalysis 1600 864 0400 814 1620 865 UA-5 Analysis 1000-500 mb thickness w/d 12 0420 815 UA-5 Analysis 1000-500 mb thickness w/d 00 1640 866 SA-1 Analysis surface 3 hrly (sectional) 15 0440 816 SA-1 Analysis surface 3 hrly (sectional) 03 1650 866A 0450 816A 1700 867 UA-3 Analysis 500 mb w/d 12 0500 817 UA-3 Analysis 500 mb w/d 00 1720 868 NA-1 Analysis nephanalysis 0520 818 1728 869 UA-3 Analysis 300 mb w/d 12 0528 819 UA-3 Analysis 300 mb w/d 00 1748 871 UA-3 Analysis 700 mb 12 0548 821 UA-3 Analysis 700 mb 00 1808 872 UA-3 Analysis 200 mb 12 0608 822 UA-3 Analysis 200 mb 00 1828 873 UP-4 Prog 500 mb baroclinic 12 hr 00 0628 823 UP-4 Prog 500 mb baroclinic 12 hr 12 1840 874 UA-2 Analysis initial 500 mb vorticity 12 0640 824 UA-2 Analysis initial 500 mb vorticity 00 1850 875 Open 0650 825 1855 876 UP-4 Prog 300/200 mb 24 hr 12 0655 826 UP-4 Prog 300/200 24 hr 00 1905 877 UP-8 Prog 500 mb vorticity 24 hr 12 0705 827 UP-8 Prog 500 mb vorticity 24 hr 00 1915 878 UP-4 Prog 700/850 mb 24 hr 12 0715 828 UP-4 Prog 700/850 mb 24 hr 00 1925 879 0725 829 1940 881 SP-1 Prog surface 24 hr 12 0740 831 SP-1 Prog surface 24 hr 00 1952 882 SP-1 Prog surface 36 hr 00 0752 832 SP-1 Prog surface 36 hr 12 2004 883 UP-4 Prog 500 mb 72 hr 12 0804 833 UP-4 Prog 500 mb 72 hr 00 2016 884 UP- 3 Analysis initial 0816 834 UP- 3 Analysis initial Prog 12, 18, 24 hr mean R. H. Prog 12, 18, 24 hr mean R. H. 2030 886 SP-3 Prog surface Package B 0822 835 SP-5 0830 836 SP-3 Prog surface Package A SP-8 SP-5 2100 887 SA-2 Analysis preliminary surface w/d 18 SP-8 2120 888 E-2 Extended forecast 5-day anomalies 0900 837 SA-2 Analysis preliminary surface w/d 06 2130 889 E-3 Progs 5 day 12 0935 839 UP- 7 Analysis initial E-4 Prog sfc extended forecast 72 hr 12 Prog 12, 24, 36 hr lifted index 2150 891 E-2 Prog sfc and 700 mb 5 day mean 0950 841 2200 892 UP- 7 Analysis initial 1000 842 Prog 12, 24, 36 hr lifted index 1010 843 2215 893 NA-1A Satellite Cloud Chart 1020 844 Ern US-Wrn Europe (Mosaic) 1040 845 SA-1 Analysis surface 3 hrly (sectional) 09 2225 894 NA-1 A Satellite Cloud Chart 1050 845A Polar Centered 40N-60W (Mosaic) 1100 846 UP-6 Forecast Error Charts 500 mb 36 hr 12 2245 895 SA-1 Analysis surface 3 hrly (sectional) 21 1110 847 SP-10 Progs sea surface 12 hr, 36 hr 00 2255 895A 1120 848 2300 896 UP-6 Forecast Error Charts 500 mb 36 hr 00 1140 849 2310 897 SP-10 Progs sea surface 12 hr , 36 hr 12 2320 898 NA-1A Satellite Cloud Chart 20W-100W (Mosaic") 2340 899 NA-1 Analysis nephanalysis NOTES: 1. All transmissions from WBC. 2. Numbers 810, 820, 830, 840, 860, 870, 880 , and 890 -Jill lot be used. 3. w/d = with data. 1-5 WBFH NO. 67-1 J ISSUANCE 10 J-67 SOUTH ATLANTIC COASTAL FACSIMILE SCHEDULE Circuit GF 10209 GMT FAX HAND- FROM Chart Description TIME GMT FAX HAND- FROM Chart Description TIME NO. BOOK NO. OR V.T. GMT NO. BOOK NO. OR V.T. GMT 0000 2401 1200 2435 0015 2402 NA-1 WBC Analysis nephanalysis 1215 2436 0030 2403 NA-1 WBC Analysis nephanalysis 1230 2437 0100 2404 NA-1 WBC Analysis nephanalysis 1300 2438 Circuit lineup 0132 2405 1400 2439 WBC Genot 0200 2406 1410 2440 0230 2407 1430 2441 NA-1 WBC Analysis Nephanalysis 0300 2408 NA-1A WBC Satellite Equatorial Mosaic #3 Australia-New Zealand 0330 2409 1500 2442 0345 2410 WBC Satellite Winds-Wrn Hem (Exper) 00 1515 2443 0415 2411 1545 2444 WBC Satellite Winds-Ern Hem (Exper) 12 0500 2412 UA-7 MIA Data 850 mb 00 1615 2445 0511 2413 UA-7 MIA Data 700 mb 00 1645 2446 0522 2414 UA-7 MIA Data 300 mb 00 1700 2447 UA-7 MIA Data 850 mb 12 0533 2415 WBC Analysis 500 mb(Exper)Sec 00 1711 2448 UA-7 MIA Data 300 mb 12 0546 2416 WBC Analysis 500 mb (Exper) Sec 1 00 1722 2449 UA-7 MIA Data 700 mb 12 0559 2417 WBC Analysis 300 mb(Exper)Sec 00 1733 2450 WBC Analysis 500 mb (Exper) Sec 12 0612 2418 1746 2451 WBC Analysis 500 tnb(Exper) Sec 1 12 0616 2419 SA-7 MIA Analysis surface (1:10 M) 00 1759 2452 WBC Analysis 300 mb (Exper) Sec 12 0656 2420 UA-7 MA Analysis 200 mb 00 1812 2453 WBC Analysis 200 mb (Exper) Sec 12 0716 2421 SA-8 MIA Analysis Top-Of-Ekman Layer (TOE) 00 1823 2454 0736 2422 UA-7 MIA Analysis 500 mb 00 1826 2455 SA-7 MA Analysis surface (1:10 M) 12 0746 2423 WBC Analysis 200 mb (Exper) Sec 00 1906 2456 UA-7 MA Analysis 200 mb 12 0759 2424 WBC Analysis 700 mb(Exper) Sec 00 1926 2457 SA-8 MA Analysis Top-Of-Ekman Layer (TOE) 12 0811 2425 NA-1 WBC Analysis nephanalysis 1946 2458 UA-7 MA Analysis 500 mb 12 0830 2426 SA-2A WBC Data final surface 00 1956 2459 0845 2427 2000 2460 SA-2A WBC Data final surface 12 0915 2428 SA-7 MIA Analysis surface (1:10 M) 06 2015 2461 NA-1 A WBC Satellite Equatorial Mosaic #1 0955 2429 NA-1A WBC Satellite Equatorial Mosaic #4 2030 2462 NA-1A WBC Satellite Equatorial 1010 2430 Mosaic (Enhanced) #7 1030 2431 2045 2463 WBC Analysis 700 mb (Exper) Sec 12 1100 2432 2058 2464 WBC Prog 700 mb(Exper) Sec 12 1130 2433 SA-2A WBC Data final surface 06 2110 2465 1145 2434 NA-1 A WBC Satellite Equatorial Mosaic #5 2123 2205 2466 2467 SA-7 MA WBC Analysis surface (1:10 M) Pro? 300 mb (Exper) Sec 18 12 2218 2468 WBC Prog 300 mb (Exper) Sec 1 12 2230 2469 SA-2A WBC Data final surface 18 2245 2470 NA-1 WBC Analysis nephanalysis 2308 2471 2323 2472 NA-1 A WBC Satellite Equatorial Mosaic #2 2338 2473 NA-1 A Wl Satellite Equatorial Mosaic (Enhanced) #8 2353 2474 1-6 WBFH NO. J 671 ISSUANCE 10-1-67 HONOLULU RADIO KVM 70 GMT HAND- BOOK NO. FROM Chart Description TIME OR V.T. GMT 0838 HNL Test /Announcement Chart - 0900 UP- 18 HNL Prog 700 mb 00 0900 UP- 16 HNL Prog significant weather 00 0923 UP- 16 HNL Prog 500 mb 00 0923 UP- 17 HNL Prog 250 mb 00 0946 UP- 16 HNL Prog 300 mb 00 0946 UP- 16 HNL Prog 200 mb 00 1009 SA-6 HNL Analysis surface 06 2038 HNL Test/Announcement Chart _ 2100 UP- 18 HNL Prog 700 mb 12 2100 UP- 16 HNL Prog significant weather 12 2123 UP- 16 HNL Prog 500 mb 12 2123 UP-17 HNL Prog 250 mb 12 2146 UP- 16 HNL Prog 300 mb 12 2146 UP- 16 HNL Prob 200 mb 12 2209 SA-6 HNL Analysis surface 18 1-7 WBFH NO. J ISSUANCE 67-7 70-1-67 SA-1; SURFACE ANALYSIS Plotted and analyzed by hand, North American area at 1:10 million scale for 0000Z plus each 3 hours. Plotting Procedures 1 . NETWORKS : Standard Network with no substitutions is used over United States 48 states only (see appendix 1). Elsewhere the data are plotted as available. Over Pacific Ocean, surface ship bulletins usually ar- rive at NMC as analysis is being finalized (i.e., 1 1/4 to 1 1/2 hours after observation time). Ship reports are entered on the analysis acetate when time does not permit plotting them on the manuscript chart. Therefore, these ship data are seen by analysts only very briefly before chart deadline. 2. MODEL: Plotting model (land stations) is a variation of abbreviated United States Model which includes all but the underlined portions of SM* s and AW s , as follows: iii Nddff Www W PPPTT N h C T h n C TT — — " L x M H T d T d app 7 R RR t S g 9 S p S p s p s p Airways reports are substituted if synoptics are not available. Sea level pressure (PPP) is rounded off to the nearest whole millibar. See appendix 2 for land and ship report models. 3. DEADLINES: Chart is plotted in several separate sections, determined by re- ceipt of data on circuits at Suitland. Sections are then taped together and full chart is available to the analyst about 1 hour after data time on the average. Analysis Procedures 1. TIME AVAILABLE: One supervising analyst and two assistant analysts work on the chart for about 20 minutes before it must be coded for teletype- writer. Another 5 minutes is then available for finalizing analysis before facsimile transmission deadline. WBFH NO. 7 ISSUANCE 2-1 67-1 101-67 2. TOOLS AVAILABLE: a. Previous 3 hourly North American analyses (corrected for later data over the Pacific and Atlantic at 00Z, 06Z, 12Z, and 18Z). b. Analysis of 1000 to 500 mb thickness field at 00Z and 12Z. c. 850 mb isotherm analysis at 00Z and 12Z. d. Radar summary from MKC valid 15 minutes before map time. e. Complete file of United States and Canadian hourly airways observations . f. Gridded APT satellite photos provided by National Environmental Satellite Center. Thickness and 850 mb isotherms are first available for use with 03Z and 15Z North American surface charts. Philosophy of Analysis Intent of analysis is to depict synoptic scale systems* of importance in weather forecasting. Therefore, smoothing of data is done to elimi- nate effects of errors and non-representativeness in observations and still retain details that are important to weather forecasting. (See page 2 of NAWAC Manual Part I.) Generally, surface fronts are located: 1. Along warm boundary of significant (e.g., where thermal shear > 25 kt. ) baroclinic zones shown on 1000-500 mb thickness and 850 mb isotherms, and along axis of maximum surface relative vorticity, i.e., along lines of strong low-level convergence, and 2. At the apex of significant (e.g., where thermal shear > 25 kt. ) thermal ridges on 1000-500 mb thickness chart, in case of oc- cluded fronts. 3. Presence (or absence) of clouds and weather is also considered in locating and classifying the intensity of fronts. For more detailed discussion see: REFERENCES: 1. STAFF A&FD, NAWAC Manual, Part I, pp. 5-7. *0n occasion, meso-scale systems shown on the Radar Analyses will be carried on the surface chart, especially if they persist for several 3-hourly charts wiw no. i issuance 67-1 JO-J-67 2-2 Depiction and Coding Fronts and instability (or squall) lines are depicted using WBAN Weather Analysis symbols (see appendix 2) further defined by 3-digit code figures with a bracket to the right. The code for type, intensity and characteristic is in accordance with "Front Group (3)" format of the Abridged U. S. Weather Analysis Code (January 1, 1949) shown in appen- dix 3. Dashed trough lines are identified by 6-digit "Pressure System Group (2)". Isobars are depicted by solid lines at 4 mb intervals labeled by 2-digit numbers, tens and units of pressure in millibars. Occasionally, inter- mediate isobars at 2 mb intervals depicted as long-dashed lines, are used in areas of weak pressure gradient. Pressure centers are indicated by "L" for low and "H" for high, labeled for central pressure by underlined 2-digit numbers in tens and units of pressure in millibars. WBFH NO. 1 ISSUANCE 2-3 671 IO-J-67 r SA-2; surface analysis Plotted and analyzed by hand, Atlantic or Pacific Ocean sec- tion of Northern Hemisphere, at 1:20 million scale for 0000Z plus each six hours. Each 6-hourly chart is issued once as a Preliminary Analysis. Plotting procedures 1 . NETWORKS : a. Only a limited network of stations is replotted over North American land areas since the complete network has already been plotted on the North American surface chart (SA-1). b. Over ocean areas, all available ship reports are plotted. Those reports which cannot be entered because of lack of space, are plotted along the border of the NMC plotted chart. A reference number (#1, #2, etc.) and the sea-level pressure (i.e., tens and units digits) are entered at the actual loca- tion of the report. 2. MODEL: Plotting model for land stations omits the RR, SpS p and s s p groups. Ship report model is identical to that used on North American sur- face analysis, SA-1 (see appendix 2). 3 . DEADLINES : For the preliminary version of the analysis, data are plotted up to approximately 1/2 hour before start of transmission of the analysis. Analysis Procedures 1. TIME AVAILABLE: Analyst receives the first copy of the plotted chart about 2 hours after observation time. The deadline on the preliminary analysis is 20 minutes before transmission time. 2. TOOLS USED: a. Previous 6-hourly hemispheric or front half (see appendix 14) surface analyses. b. Hemispheric hand-analysis of 1000-500 mb thickness field at 00Z and 12Z. c. Norwegian Frontal Models (see appendix 4). d. Numerical Surface Analysis based on a 1+30 data cut-off at 00Z and 12Z. WBFH NO. I ISSUANCE 2-5 67-1 10-1-67 e. Mosaics of gridded satellite pictures, digitized and actual, and annotated nephanalysis provided by National Environmental Satellite Center. Philosophy of Analysis Intent of the analysis is to portray the macro- structure of the polar front and its associated baroclinic zones around the hemisphere. The evolution of all cyclones and anticyclones along and on either side of the baroclinic zone are included in this portrayal. The arctic front is portrayed also when significant weather and temperature changes are as- sociated with it. The Norwegian Frontal Model (see appendix 4) is followed more faith- fully over the oceans where data networks are sparse. (Over land areas, more frequent and regular data plus terrain- induced peculiarities often require deviations from the standard model). Generally, surface fronts are located: a. Along warm boundary of significant (e.g., where thermal shear >25 kt.) baroclinic zones shown by 1000-500 mb thickness and 850 mb isotherms, and along axis on maximum surface relative vorticity, i.e., along lines of strong low-level convergence; and b. At the apex of significant (e.g., where thermal shear >25 kt.) thermal ridges on 1000-500 mb thickness chart, in case of oc- cluded fronts. c. Presence (or absence) of clouds and weather is also considered in locating and classifying the intensity of fronts. For more detailed discussion see: REFERENCES : 1. STAFF A&FD, NAWAC Manual, Part I, pp. 5-7. Depiction and Coding As on the North American chart, fronts are depicted using WBAN analysis symbols (see appendix 2) and further explained by a 3-digit code figure according to the "Frontal Group (3)'* format of the Abridged United States Weather Analysis Code (see appendix 3). Isobars are depicted by solid lines at 4 mb intervals labeled by 2-digit numbers, tens and units of pressure in millibars. Occasionally, inter- mediate isobars at 2 mb intervals, dashed lines, are used in areas of weak pressure gradient. Pressure centers are indicated by "L" for low and "H" for high, labeled for central pressure by underlined 2-digit numbers in tens and units of millibars. WBFH NO. 7 ISSUANCE 67-1 10-1-67 2-6 SA-2A; SURFACE DATA Plotted by hand, Atlantic Ocean section of the Northern Hemisphere, at 1:20 million scale at 0000Z plus each six hours. Plotting Procedures 1. NETWORKS AND MODELS: Networks and models are the same as those described under charts SA-1 and SA-2. 2. AREA The area covered is a variation of that shown in appendix 15, excluding Europe but including the Gulf of Mexico, Central America, and northwestern South America. 3 . DEADLINES : Data are plotted up to about one-half hour before transmission time. WBFH NO. J ISSUANCE 2_7 67-1 10-1-67 SA-3; SURFACE ANALYSIS Hand analyzed for front half (see appendix 14) of Northern Hemisphere. Transmitted with 1000-500 mb thickness analysis superimposed, without data for OOO0Z and 1200Z at 1:30 million scale. Plotting Procedures Although no plotted data are shown on this chart, networks and models are identical to those for the preliminary Surface Analysis, Atlantic and Pacific sections (with data), SA-2. Data are plotted up to approximately 1/2 hour before transmission time. Analysis Procedures Surface Analysis Tools used and philosophy of analysis are identical to those for Preliminary Surface Analysis, Atlantic and Pacific sections (with data), SA-2 which is revised for data up to 3 1/2 hours after ob- servation time. The analysis at 1:20 million scale is completed about one hour before transmission time and traced on reduced scale chart. The 1000-500 mb thickness analysis 1. TIME AVAILABLE: This analysis is based on plotted data available up to 3 1/2 hours after observation time. 2. TOOLS AVAILABLE: a. Standard thickness frontal model (see appendix 4). b. 500 and 1000 mb analyses. c. 500 mb 12 hour prog. 3. PREPARATION: Analysis performed on 1:20 million scale is based on: a. Thermal winds computed by vector subtraction of geostrophically measured sea level winds from reported 500 mb (or 18,000 ft) winds. b. Thickness values determined by subtraction of reported or com- puted 1000 mb heights from reported 500 mb heights. c. Graphical subtraction of 1000 mb contours from 500 mb contours. WBFH NO. I ISSUANCE 2_9 67-1 10-1-67 Over areas where data is plentiful, thickness isopleths are drawn to fit plotted thickness values and to approximate standard thick- ness-frontal model (see appendix 4). Over areas with little or no data, thickness contours are estimated first by graphically sub- tracting 1000 mb from 500 mb contour analyses. Adjustment of thickness pattern to conform to model shown in appendix 4 may re- sult in modification of 1000 mb or 500 mb analysis, or both. REFERENCES : 1. STAFF A&FD, NAWAC Manual, Part I, pp. 15-19. Depiction and Coding Depiction and coding of fronts is identical to that used on SA-1 and SA-2 surface analyses (see appendices 2 and 3). Isobars are depicted by solid lines at 8 mb intervals labeled by 2-digit numbers, tens and units of pressure in millibars. Occasionally, inter- mediate isobars at 4 mb intervals, dashed lines, are used in areas of weak pressure gradient. Pressure centers are indicated by "L" for low and "H" for high labeled for central pressure by underlined 2-digit numbers, tens and units of millibars. Thickness isopleths are depicted by dotted lines at 60 meter intervals labeled in decameters. WtFH NO. J ISSUANCE 671 10-1-67 2-10 S A-4; WEATHER DEPICTION ANALYSIS Plotted and analyzed by hand for United States, southern Canada, and northern Mexico at 1:10 million scale for 0100Z plus each 3 hours. Plotting Procedures 1 . NETWORK : No standard network is used. Chart is plotted from hourly airways observations. Air Force Base observations are used to fill in gaps in the network, especially during night hours when some civilian reporting stations do not operate. 2 . MODEL : The plotting model is an abbreviated version of the complete avia- tion report which includes a) significant weather, b) visibility c) total sky-cover, and d) ceiling height (see appendix 5). All ceiling heights (i.e., lowest cloud height with more than 5/10 coverage) are plotted. When total coverage is 5/10 or less, then height of lowest scattered layer is plotted. Visibilities over 6 miles are not plotted. 3 . DEADLINES : The base-chart is divided near the mid-continent so that two char- tists may plot simultaneously from different Service A circuit listings. The plotting deadline is 45 minutes after the synoptic hour. The plotted chart is then reproduced for internal use which requires 5 minutes. Analysis Procedures 1. TIME AVAILABLE: From 15 to 20 minutes are available for analysis of this chart. Actual analysis time varies depending on the amount and complexity of the clouds and visibility to be depicted. 2. TOOLS AVAILABLE: a. Previous weather depiction analyses. b. Latest surface analysis, usually for the previous hour. WBFH NO. J ISSUANCE 2_H 671 10-1-67 Philosophy of Analysis This analysis portrays the synoptic-scale structure of ceiling and visibility in two operational categories, vis: 1. Ceiling less than 1000 feet and/or visibility less than 3 miles, solid lines. 2. Ceiling 1000 to 5000 feet and visibility 3 miles or more, scalloped lines. The analysis of these two operational categories is shown as continuous within the network of reports plotted on the chart. Smaller-scale fluctuations in category due to variations in local terrain, etc., are not intended to be portrayed on this chart. The chart is designed primarily as a briefing tool to alert aviation interests to the location of critical or near-critical operational minimums at terminals in the United States and surrounding land areas. WifH NO. I ISSUANCE 67-1 101-67 2-12 SA-5; RADAR ANALYSIS (ADUS) MKC Contiguous United States east of Plateau, 1:10 million scale for 0245Z plus each 3 hours and selected 5-minute sections of United States for 0445Z, 0745Z, 1945Z, 2145Z and 2245Z. Plotting Procedures 1 . NETWORKS : All WSR-57 reports, plus 12 Air Force CPS-9 radar reports and selected SP-1, WSR-1, 3, and 4 radar reports which comprise the basic network are plotted routinely as they are received. Ad- ditional WSR-1 and 3 reports are plotted whenever they are per- tinent. Salt Lake City ESSA-FAA ARTC radar data are entered on the 1445Z and 2045Z charts. (See appendices 6, 7) When convec- tive activity is widespread, reports are plotted by two technicians. 2. MODEL: Reports are plotted each hour, using a slightly modified version of the standard facsimile radar chart nomenclature. 3 . DEADLINES : The raw data or the SD* s are taken at H+30 (30 minutes past the hour). Receipt of reports (SD* s) begins at H+45 which are plotted until all received or until H+80 (maximum of 35 minutes of plotting t ime ) . Analysis Procedures 1. TIME AVAILABLE: The time for analysis varies from 3 to 10 minutes (H+90 total elapsed time) depending on the weather situation. The next step is to code the analysis for transmission on Service A and RAWARC. Two men are involved in this 5 minute step; the analyst dictates the coded information and another man types it. Echo outlines are traced from the master plotting chart, using light reduction equip- ment. Adjacent smaller areas of similar echo are sometimes grouped as a single area if this should not result in a change of category (i.e., from broken to scattered). Thus, the analysis (including preparation of the SD-1 word summary) is accomplished between H+80 and chart filing time at approximately H+110 (about 65 minutes after time of observations). WtFH NO. I ISSUANCE 2_i3 67-1 10-1-67 m 2. TOOLS USED: a. Previous hourly RADU plots of radar activity are used for continuity. b. Current standard synoptic surface and upper air analyses (plus hourly sectional surface analyses for areas of intense activity) . c. Hourly sequences for point verification of precipitation, location, type, and intensity. d. Current status check of all radars plus intelligence of what type radar used to report echoes. Philosophy, of Analysis The intent of the radar analysis is to depict the mesoscale and general macroscale distribution of precipitation patterns (including layers of "wet" clouds with which surface precipitation may or may not be occur- ring). Since the radar coverage is frequently overlapping and individ- ual radars are observing the echo from different angles and ranges (therefore heights), the analysis must include an intelligent interpre- tation of the overlapping data. A further consideration in analysis is that echoes may be reported by high powered 10 cm radars (WSR-57), high powered 3 cm radars (CPS-9) or low powered 10 cm radars (WSR-1 or 3). Each of these have quite different observational capabilities which must be considered in the final analysis. REFERENCES : 1. Foster, Jr., H. E., "Methods Used in the Production of the Radar Summary Facsimile Chart", Notes to Forecasters ESSA, Weather Bureau, May 1965. Depiction Analysis of radar echoes is depicted in the format of appendix 8, "Explanation of Radar Summary Chart". In addition, the radar type at each site and the areas beyond normal operational range of the radars are identified. A legend of radar types is included on each transmitted chart. Areas where there is no radar coverage due to the absence of radars or beyond 75 nautical miles from WSR 1, 3, and 4, and 125 nautical miles from WSR 57, CPS 9, SP 1, FPS 41, and FAA radars are stippled as a permanent feature of the base map. When echoes are observed beyond the normal operational range of the radars, they are superimposed on the stippling. WtFH NO. J ISSUANCE 67-1 10-7-67 2-14 Tornado Watch areas are outlined by dashed lines and Aviation Severe Weather Bulletin areas by dotted lines; "boxes" are labeled by watch number. Consecutively numbered suffices are added if there is more than one box in the weather watch. The weather warning number and valid ending time (Z) corresponding to each box number are indicated in the lower left portion of the chart in the format: WW NR VALID TIL WBFH NO. 1 ISSUANCE 2-15 67-1 10-1-67 ♦ SA-6; HNL SURFACE ANALYSIS Plotted and analyzed by hand for the tropical Pacific area (see appendix 45-Area I) on a 1:20 million scale Mercator chart for 0600Z and 1800Z. Tools Available 1. Previous six hourly analysis. 2. 1000-500 mb and 1000-250 mb thickness fields. 3. At higher latitudes, surface, thickness and upper air charts from NMC. 4. Local APT pictures (morning) from the West Coast to Japan. (The Western picture strip is relayed fromWBAS, Wake Island.) 5. NESC cloud mosaics of the tropical Pacific area in the evening. 6. Typhoon/hurricane advisories. 7. Pilot reports of significant weather occurrences. Philosophy of Analysis The philosophy is similar to that of NMC in higher latitudes except the isobaric analysis is considered to represent the tropical wind field poorly. Depiction Isobars are depicted by solid lines at 4 mb intervals and are labeled by 2-digit numbers, tens and units in millibars. Occasionally inter- mediate isobars at 2 mb intervals are entered as dashed lines. Pressure centers are indicated by "L" for low and "H" for high. Fronts are depicted using WBAN Weather Analysis symbols (see appendix 2). Plotted data are deleted from the chart to reduce blurring during radio facsimile transmission. WBFH NO. J ISSUANCE 2-17 67-1 70-1-67 SA-7; SURFACE ANALYSIS - MIA Plotted and analyzed by hand for 0000Z plus each 6 hours. Area bounded by 45 N latitude and the Equator; 125 W and 10 W longitude, 1:10,000,000 scale, modified Mercator pro- jection as shown in appendix 52. Plotting Procedures 1 . NETWORKS : Over the continental U. S., only selected land stations south of 36 N are plotted (see appendix 53). Elsewhere as many land sta- tions are plotted as can be entered on the chart without undue crowding. Nearly all ship reports are plotted, and where crowding occurs the additional reports are plotted off position in sparse data areas. Unplotted ship reports are given to the analyst to scan. The reports from Africa and South America as well as ship reports that are not available to the analyst at chart deadline, are entered as late data. 2. MODEL: Plotting model (see appendix 2) is a variation of abbreviated United States model which includes all but the underlined portions of SM' s and AW s, as follows: iii Nddff WwwW PPPTT N^h^C^ T d T d app 7RRR t S s 9SpSpS p s p ld w d w P w H w Airways reports are substituted if synoptics are not available. Sea level pressure (PPP) is rounded off to the nearest whole millibar. 850 mb heights are plotted instead of sea level pres- sure for certain stations in Africa and South America at high elevations. Sea water temperatures are plotted for United States stations 699, 211, 231, 202, and 251, and for selected ships. 3. DEADLINES: The entire chart is plotted by one chartist. On the 0000Z and 1200Z charts, analysis begins 4 1/2 hours after data time. Analysis of the 0600Z and 1800Z charts begins two hours after data time. Analysis Procedures 1. TIME AVAILABLE: One analyst prepares the initial analysis of each chart. Fac- simile transmission deadlines allow a period of two hours for the analysis of each 0000Z and 1200Z chart - 1 1/2 hours for the WBFH NO. I ISSUANCE 2_19 67-1 10-1-67 for the 1800Z chart and only one hour for the 0600Z chart. After each chart has been transmitted, late data is plotted and the analysis is reworked — where necessary — to provide continuity for analysis of the succeeding chart. On the 0000Z and 1200Z analyses (see appendix 54), a brief type- written script is added to the chart to provide comments on or explanation of features not evident from the analyses themselves; or, more frequently, to identify features or trends observed by weather satellites. 2. TOOLS AVAILABLE: a. The NMC surface analysis for North America, and the North Atlantic Ocean. b. Previous 6 hourly surface analyses. c. T.O.E. (Top of Ekman Layer) wind analyses at 0000Z and 1200Z. d. Six hourly pibals for selected levels. e. Gradient level pibals entered directly on the chart in non-reproducing light blue pencil. f . APT satellite pictures as received at MA plus a far eastern pass received at San Juan, P. R., and relayed to MLA. g. Digital photo mosaic received by facsimile from NESC in time for use on 0000Z analysis. h. Nephanalyses on the same scale and projection for the area north of 30 S, and on a polar stereographic projection for the area south of 30 S. i. Mean monthly charts of surface wind, pressure, and precipi- tation. j. Radar reports - domestic and foreign. k. Aircraft reconnaissance reports. Philosophy of Analysis The intent of the analysis is to portray synoptic scale systems of importance to weather depiction and forecasting. Therefore, smoothing of data is done to eliminate effects of errors and non-representative- ness in observations. Wherever the data permit (as when an unusual concentration of ships occurs; aircraft reconnaissance, radar, or satellite observations are available, etc.) meso-scale systems are also portrayed. In general: WtfH MO. I ISSUAHCt 67-1 10-1-67 2-20 1. Surface positions of fronts over the northern portions of the chart are copied from and/or blended into the NMC analyses for the same areas. 2. Surface positions of fronts over the southern portions of the chart are derived largely from the NMC nephanalyses, from what surface reports are available, and from coded analyses sent by the meteorological services of countries in Africa and South America. 3. Surface positions of fronts elsewhere are determined by stand- ard methods except that no thickness analysis is done. 4. Tropical storms, hurricanes, and occasionally other tropical disturbances such as easterly waves, are frequently well de- picted by the pressure analysis. However, the majority of weaker systems near the equatorial latitudes, and in particular the daily position of the intertropical convergence zone (or zones), are best shown by the streamline analysis on the T.O.E. chart. a. Where insufficient data are available to define the systems, an effort is made to depict a flow pattern in the Atlantic similar to that shown in appendix 55. b. Where insufficient data are available to define the pres- sure field, the pressure analysis is made to follow con- tinuity first and then gradually to approach a normal pattern for the season. 5. Heavy reliance is placed on the observations received from the weather satellites. Depiction and Coding Fronts, troughs, ridges, highs, and lows are depicted with standard NMC Weather Analysis Symbols (see appendix 2). Easterly waves, shear lines, reflected troughs, and the ITC are depicted by means of a heavy dashed line with the appropriate label stamped along it. Tropical disturbances are identified by the stamped symbol "T r) ". These are defined as synoptic scale areas of disturbed weather persisting for 24 hours or longer but lacking the organized circulation required for classification as depressions. Tropical depressions are identified by the stamped symbol "T " with subscript numbers SSNNDD, where SS is day of month the depression is named (XX for unnamed depressions), NN is the seasonal sequential tropical cyclone number assigned to the depression, and DD is the num- ber of GMT calendar days the depression is carried on the chart. WBFH NO. ? ISSUANCE 2-21 67] 101 - 67 Tropical storms are identified by the symbol M T S " and a printed name with subscript numbers SSNNDD as above. m Hurricanes are identified by the symbol "S" with printed name and subscript numbers as above. WBFH NO. I ISSUANCE 67-1 70-7-47 2-22 m SA-8; SURFACE ANALYSIS (TOP OF EKMAN LAYER) MIA Plotted and analyzed by hand at 0000Z and 1200Z for the area bounded by 35 N and 40 S latitude and 150 W and 20 E longitude on a 1:20 million scale modified Mercator pro- jection (see appendix 52). Plotting Procedures 1 . NETWORKS : All surface ship winds and upper winds at 3,000 feet are used. Land stations are used over South America and Africa south of 10 N latitude. Cloud analyses from satellite photographs are also entered with the primary emphasis on major convective cloud systems. 2. MODEL: a. PIBAL and RAWIN data — the standard NMC model is used except that the wind shaft is extended beyond the station circle to distinguish those types of data from the surface wind data plotted on the same chart: b. Surface synoptic data — an abbreviated NMC model is used: Land Ships TTV u D s v s WW I N ) PP d w d w?w H w d s d sP s^s Note: Over areas also covered by the sea level chart, only wind data (surface and 3,000 ft) are plotted on the TOE chart. c. Direction of motion of low clouds — plotted as a 3/8" arrow above the station circle: 3 . DEADLINES : Analysis of this chart begins four hours after data time. Data received after that time are plotted in red ink, but this dis- tinction is not discernible on the transmitted copy. 2-23 WBFH NO. ? 67-7 ISSUANCE 10-1-67 Analysis Procedures 1 . PREPARATION : This chart is analyzed in close coordination with the sea level chart and is designed to give a representative flow pattern and related cloudiness for the low troposphere. A pattern of stream- lines is constructed with due attention to cloud organization, pressure pattern, and continuity. 2. TOOLS AVAILABLE: a. NMC surface analysis for North America and the North Pacific Ocean. b. Previous 6 hourly surface analyses. c. Previous TOE layer analysis. d. Six-hourly pibals for selected levels. e. APT satellite pictures as received at MIA plus a far eastern pass received at San Juan, P. R. , and relayed to MA, f. Dig'tal photo mosaics. g. Neyhanalyses. h. Mean monthly charts of surface wind, pressure, and precipi- tation. i. Radar reports - domestic and foreign. j. Aircraft reconnaissance reports. 3. TIME AVAILABLE: One and a half to two hours are allotted for the analysis of this chart. Philosphy of Analysis The sea level chart and the TOE chart complement one another. If the information available could be satisfactorily analyzed on a single chart, that would be preferable. This is impractical, so the sea level chart is drawn to provide a larger scale presentation of pressure and frontal patterns over a limited area, and the TOE chart to provide a low latitude streamflow and nephanalysis in both hemispheres. The TOE chart is analyzed on the same base map as that used for the upper-air analyses to simplify procedures for achieving vertical consistency through all levels of analysis. WBFH NO. 1 ISSUANCE 67-1 10-7-67 2-24 The cloud analysis depicted on this chart aids in establishing the position of the ITC, other lines of convergence, and areas of disturbed weather. Use is also made of an unpublished study which indicates that the surface wind over the oceans in equatorial latitudes is most often nearly parallel to the orientation of cumulus cloud lines as viewed by weather satellites. REFERENCE : 1. Gaby, Donald C., "Cumulus Cloud Lines Vs. Surface Wind in Equatorial Latitudes", (Manuscript submitted for Publication), Tropical Meteorological Center, ESSA, Miami, Florida, September 1966. Depiction and Coding 1. Wind flow is depicted by streamlines and isotachs. 2. In the satellite photographs, areas covered, or mostly covered, by bright clouds are outlined in a heavy solid line and shaded in lightly with a screen mesh underlay. 3. Circulation centers are identified by stamped symbol as follows: C Cyclone A Anticyclone A. ... .Thermal anticyclone, defined as smaller scale anti- cyclonic circulations found in the upper troposphere, formed essentially through convective release of latent heat and accompanied by cloud or rainy conditions. E Equatorial circulation centers which can not readily be classified as cyclones of either hemisphere. 4. Fronts are depicted by means of the standard pipped lines. (See appendix 2.) 5. Troughs, shear lines, easterly waves, and the ITC are shown as heavy broken lines with appropriate titles stamped along them. WBFH NO. ? ISSUANCE 2-25 67} 10-1-67 UA-1; UPPER AIR ANALYSIS For major portion of North America and contiguous areas of the eastern Pacific and western Atlantic Oceans (FAX Section 1 as shown in appendix 13) 1 on a 1:20 million scale for 0000Z and 1200Z. The analyses are: 1. 850 and 500 mb: hand plotted and analyzed. 2, 700, 300, and 200 mb: computer analyzed with anal- yses and data reproduced by Digifax process. A. 850 mb and 500 mb Charts Plotting Procedures 1 . NETWORKS : All available radiosonde, rawinsonde, pibal, and weather reconnais- sance reports are plotted by hand. Over ocean areas, available AIREP and reconnaissance reports are plotted according to the cri- teria listed in paragraph 2 of appendix 9. In actual practice, transmission of the 850 mb and 500 mb analyses within 2 1/2 hours of observation time restricts plotting of AIREP data on these charts. 2. MODELS: a. Station model used to plot radiosonde, rawinsonde and pibal re- ports is shown in paragraph 1 of appendix 9. On the 850 mb chart, where observing station is 'above the 850 mb surface, computed temperatures 2 are plotted with a bracket to the right. b. The station models used to plot AIREP and reconnaissance re- ports are described in appendix 9, paragraphs 2 and 3. 3 . DEADLINES : Deadlines for entering all data on hand-plotted and analyzed 850 and 500 mb charts are about 1 1/2 hours after observation time. """A larger section (i.e., la) including all of Alaska is used for 500 mb and a smaller section for 850 mb analyses. Temperatures are computed by assuming standard atmosphere lapse rates in win- ter and almost dry adiabatic lapse rates in summer between 850 mb and 775 mb. Estimates are made as follows: 775 mb plus 5° C in winter and plus 7° C in summer; at Ely, Nevada: 725 mb temperature plus 10° C all seasons. WBFH NO. J ISSUANCE 3_1 67-J JO-1-67 Analysis Procedures 850 mb Chart 1. TIME AVAILABLE: One man completes the analysis in about 3/4 hour by direct analysis of the data. 2. TOOLS AVAILABLE: a. Surface analysis for the same synoptic hour. b. Previous 850 mb analysis, or "continuity". c. Hand recomputations of the 850 mb temperatures over western United States. (See page 21 of NAWAC Manual, Part I). Heights at 850 mb are also available from the 12Z airway reports to use in the analysis over the inter- mountain area of the western United States. The frontal intersections at 850 mb are located along the warm boundaries of baroclinic zones (as revealed by the 850 mb isotherms) where relative (cyclonic) vorticity is a maximum, in other words, along lines of strong low level convergence. Reasonable frontal slopes from 850 mb to the surface are also used to interpolate fronts between upper-air observations. 500 mb Chart 1. TIME AVAILABLE: One supervising analyst and two assistant analysts complete the analysis in about 1/2 hour (1 1/2 man hours) by direct analysis of the data. 2. TOOLS AVAILABLE: a. Location of surface fronts and centers. b. Previous 500 mb analyses, or "continuity". c. The latest 12-hour NWP prognosis of the 500 mb flow, based on a computer analysis made from a data cut-off time 8 hours after the previous set of observations. Generally, the 12-hour prognosis is weighted most heavily over ocean areas and Mexico. WBFH NO. 7 ISSUANCE 671 101-67 3-2 Depiction Fronts (on the 850 mb analysis) are depicted using WBAN analysis symbols identical to those used on surface analyses (see appendix 2). Contours are depicted by solid lines at 60 meter intervals labeled by 3-digit numbers in decameters and also in D-values, the departure of the height in feet from the height of a standard atmosphere at the pressure surface (1457 meters at 850 mb and 5580 meters at 500 mb). Occasionally, intermediate contours drawn as long-dashed lines at 30 meter intervals are used to delineate patterns in areas of weak gradient. Circulation centers are identified by the conventional "L" for lows and "H" for highs. Isotherms are drawn as short dashed lines at 5° C intervals, so labeled. These also represent lines of equal potential temperature. B. 700, 300, and 200 mb Charts Computer Analysis Procedures 1. Automatic Data Processing The computer analysis proceeds as a separate operation from the hand-plotted analyses already discussed. The analyses which are done in the computer use data which are fed directly from national and international teletype circuits, through a communications com- puter (IBM 360 System), to the main NMC computer (IBM 7094). Then an ADP program decodes, checks, recomputes and lists all available radiosonde, rawinsonde, pibal, reconnaissance AIREP, and any bogus* reports. A brief description of the ADP program can be found in: REFERENCES : 1. Burnett, F. W. , "The Role of the Computer in Meteorology", Weatherwise. Vol. 18, No. 5, October 1965. Civilian AIREP reports are edited and coded for use in ADP at five Weather Bureau field offices (see appendix 10). Approximately 75 military AIREPS are also made available to NMC by each data cut-off time from the USAF Computerized Flight Planning Section at Suitland. These reports are primarily over the Atlantic and Pacific Oceans, although a few North American reports are available. *Bogus reports are any height, wind or temperature data that have been computed, extrapolated, or otherwise manufactured by a monitoring analyst and inserted by hand. WBFH NO. ? ISSUANCE 3-3 67-1 10-1-67 Deadlines for data collection for the computer analyses are as follows: Computer Data Chart Deadline (after 00Z or 12Z) 700 mb 1 1/2 hours 300 mb 3 hours and 25 minutes 200 mb 3 hours and 25 minutes 2. Analysis Procedure Details of NMC* s complex and ever-changing computer analysis proce- dures will not be given here. The most recent references on this subject are: REFERENCES : 1. Gustafson, A. F. , and McDonell, J. E., "The Derivation of First-guess Fields for Objective Analysis, 1000 mb to 500 mb" , NMC Technical Memo #31; or 2. Kulawiec, M. H. , "The New Machine Analysis" Notes to Forecasters, May 1965. The computer analysis involves three procedures: a. Obtaining the best "first guess" of values of parameters (height, temperature) at grid points from a short range prog- nosis (12 hours) or from extrapolation by statistical regres- sion equations from values of parameters at grid points already determined by analyses at other levels. The references listed above detail the methods of obtaining guess fields at 1000, 850, 700, and 500 mb. Appendix 12 outlines the present methods for 300, 200, and 100 mb. b. Adjusting these guess values by a weighted average of the new observational data available in an influence area surrounding each grid point. The size of the influence area is controlled by the amount of data available. Over North America this in- fluence area averages about 400 nautical miles in radius. Over ocean areas, where observations are much more sparse, a much larger (up to 1000 nautical miles in radius) influence area is searched before enough observational data for a new determina- tion of grid point values are obtained. Often, over the Pacific Ocean especially, the guess field becomes the final data field when no observations are available at any level. WBFH NO. J ISSUANCE 67-1 70-7-67 5-4 c. The grid point data is run through a data processor on the IBM 7094 computer which determines a closely spaced set of x-, y-coordinates for the height contours and isotherms (also isotachs) of the analysis by quadratic interpolation from the grid point values. The coordinates may be traced out by the Curve Follower or Digifax process to give the finished analysis of the grid point data. Geostrophic winds are determined at each grid point from the final height data for a "first guess" field. The grid point winds are adjusted for actual wind observations using the same technique as was used for the height and temperature fields. Over dense-data areas, the observed wind velocities determine the grid point values. In sparse-data areas the grid point wind velocities are based primarily on the geostrophic wind derived from the height differences between grid points. 3. philosophy of Analysis Computer analyses are made from data derived at a network of grid points spaced about 180 nautical miles apart (see appendix 11). Systems with wave lengths (trough- to- trough distance) less than 200 nautical miles will not be evident on these analyses. Furthermore, smoothing during the computer analysis generally eliminates most systems with wave lengths less than 400 nautical miles. Derivation The analyses are produced by the Digifax process as follows: 1. The data processor output of x-j y-coordinates for points on the lines representing each isopleth also contains the locations of sta- tion circles and sets of numbers for the data at each observation point. 2. The output is fed into a cathode ray tube activating an electron beam which traces out the x-j y-coordinates of the isopleths, the station circles and the observational data. 3. The electron beam impinges on a phosphor target about 40 mm square on the face of the CRT causing an image of the isopleths and data to appear momentarily. 4. The image is reflected by a mirror into a camera exposing a film frame about 30 mm square. At the same time, an electronic flash through a slide sends an image of the appropriate geographical back- ground through the mirror on to the same film frame. 5. The microfilm is processed and mounted on an aperture punch card with information as to type of chart, date and time prepunched and printed on the card, 6. The microfilm is enlarged to hard copv suitable for facsimile transmission. wtm NQ , (SS(MNa 3-5 67-1 10-1-67 Depiction Observational data are depicted as follows: HHH fff The wind direction is indicated by a shaft with a short barb at right angles plotted to 36 points. The wind velocity, fff, is given by a 3-digit number in knots. The height, HHH, is in meters with thousands digit omitted at 700 mb; in decameters at 300 mb; and in decameters with ten-thousands digit omitted at 200 mb. The temperature, TT, and dewpoint T^T^, are in degrees Celsius. In ad- dition temper ature-dewpoint spread of 5° or less is indicated by filling in of the station circle on 700 mb analysis only. Because of the necessity of allowing for space to plot the observational data with no overlap, only about 60% of the available observations may be plotted. These are selected from a listing of priority stations which are plotted routinely, unless all or a portion of the data is missing when a nearby station is substituted. However, the analysis is based on all of the available observations. There is no backup procedure for hand plotting of data if the Digifax program fails. Digifax charts are limited to 2 sets of isopleths. Height contours are depicted as solid lines on all charts. They are hand labeled by 3-digit numbers in decameters (except with ten-thousands digit omitted at 200 mb), In addition, base contours, the heights of a standard atmosphere at the particular constant pressure surface, are indicated by short-dashed lines for reference values. These values are 306 decameters with contour in- tervals of 60 meters at 700 mb; and 924 decameters at 300 mb and 1188 decameters at 200 mb with contour intervals of 120 meters at both these levels. Circulation centers are identified by + with the conventional M L" for lows and "H" for highs; labeled by 3-digit numbers, in meters with thou- sands digit omitted at 700 mb and in decameters at 300 and 200 mb (ten- thousands digit omitted at 200 mb). Dashed lines depict isotherms at 5° intervals hand labeled in degrees Celsius on 700 mb analysis; and isotachs at 20 knot intervals hand labeled in knots on 300 and 200 mb charts. Jet axes are not explicitly indicated; their positions must be inferred from the isotach patterns and plotted wind velocities. WBFH NO. I ISSUANCE 671 10-1-67 3-6 There is no backup procedure for plotting data when the Digifax program fails. At these times, the Curve Follower output of analyzed contours, isotherms and isotachs will be transmitted without observational data. Addendum: Production of 300 mb and 200 mb analyses by the Facsimile Group Converter in lieu of Digifax was begun November 7, 1967. Depiction by the new system is as follows: 1. Almost all land and ship reports and also aircraft reports can be plotted. When reports are so close together that printed data overlaps, one is omitted. 2. The charts are limited to two sets of isopleths also. Contours are drawn as solid lines at 120 meter intervals with no labeling. The 9480 and 9000 meter contours at 300 mb and the 12240 and 11760 meter contours at 200 mb are drawn as heavier solid lines. Isotachs are drawn as dashed lines at 20 knot intervals with no labeling. Values must be inferred from plotted velocities. 3. Highs are indicated as + and lows as - with labels in decame- ters printed in white within a black rectangle. 4. The plotting model for aircraft reports plotted over ocean areas is: rr HHH \^o fff V ""^ AIII The wind direction is indicated by a shaft with a short barb at right angles plotted to 36 points. The wind velocity, fff, is given by a 3-digit number in knots. The altitude of the aircraft, HHH, is plotted in tens of feet with initial digit omitted (500 = 35,000 ft.). The identification of the aircraft report, AIII, refers to the ADP listing. WtFH NO. 1 ISSUANCE 3-7 67-1 10-1-67 UA-2; upper Am analysis Computer analyzed without plotted data for North American side of Northern Hemisphere (Front Half Section) 1 on a 1:30 million scale chart at 0000Z and 1200Z. These analyses are: a. 500 mb analysis, including contours and isotherms. b. 300 mb analysis including contours and isotachs, with selected Pacific and Atlantic data plotted by hand. c. Initial 500 mb vorticity analysis, including isopleths of absolute vorticity. Computer Procedures; ADP These analyses are based on Automatic Data Processing (ADP) which begins at 3+25 hours after observation time when data, available in the stor- age facility of the NMD Communications Computer (IBM 360 System), are fed into the main NMC computer (IBM 7094). Then the ADP program decodes, makes hydrostatic checks, recomputes and lists all available radiosonde, rawinsonde, pibal, reconnaissance and AIREP reports. Civilian AIREP reports, edited and coded at five Weather Bureau field offices are occasionally available for these analyses (see appendix 10). Approxi- mately 75 military AIREP* s primarily over the ocean areas are available to NMC by the data cut-off time from the USAF Computerized Flight Planning Section at Suitland. A brief description of the ADP program can be found in: REFERENCE : 1. Burnett, F. W. , "The Role of the Computer in Meteorology", Weatherwise, Vol. 18, No. 5, October 1965. Computer Analysis Procedures Details of NMC* s complex and ever-changing computer analysis procedures will not be included here. The most recent references available on this subject are: REFERENCES : 1. Gustafson, A. F. , and McDonell, J. E., "The Derivation of First Guess Fields for Objective Analyses, 1000 mb to 500 mb", NMC Tech Memo #31, or 2. Kulawiec, M. H. , "The New Machine Analysis", Notes to Forecasters, May 1965. See appendix 14. 2 By NMC convention, the time is listed as number of hours plus number of minutes after observation time. WBFH NO. J ISSUANCE 3-9 67-T 10-1-67 Philosophy of Analysis The most important points to understand when using computer analyses are: 1. Computer analyses are made from data derived at a network of grid points spaced about 180 nautical miles apart (see appen- dix 11). The positions of isopleths drawn by the Curve Follow- er are interpolated from values at points on this fixed grid. Systems with a wavelength (e.g., troughs, lows) less than 200 nautical miles in extent will not show up on these analyses. Furthermore, smoothing during the computer analysis eliminates "wiggles" or systems smaller than 400 nautical miles in extent. 2. The computer analysis involves two main procedures: a. Obtaining the best guess of values of parameters (height, temperature) at grid points from a short-range prognosis or by extrapolation with statistical regression equations from values of parameters already analyzed at other levels. The two references listed above, detail the method of obtaining the 500 mb guess field. The 300 mb guess is obtained as shown in appendix 12. b. Adjusting these guess values by a weighted average of the new data available in an influence area surrounding each grid point. The size of the influence area is controlled by the amount of data available. Over the United States, this influence area averages about 400 nautical miles in radius. Over ocean areas, where observations are few and far between, a much larger (up to 1000 miles) influence area is searched before enough data for a new analysis is obtained. Often, over the Pacific ocean, the guess field becomes the new analysis when no new data are available at any level. Computation of Parameters 1. Contours and isotherms These are computed using the ADP (automatic data processing) and analysis procedures described in the preceding paragraphs. 2, Isotachs On the 300 mb analysis, the isotachs are based on a wind analysis using geostrophic wind as a first-guess and adjusting this by the wind observations. Over dense data areas, the new data determine the isotachs by the same method and within the same scale limita- tions already listed for contour and isotherm analyses. WtFH NO. 1 ISSUANCE 67-1 10-1-67 3-10 Over sparse-data areas, the isotachs are based primarily on the geostrophic wind derived from the contour spacing. 3. Absolute vorticity The absolute vorticity (7]) consists of the relative vorticity plus the Coriolis Parameter, or earth's vorticity, viz: 1 - G + * 1 _5 It has the dimensions of sec X 10 on the NMC charts. The value of f varies from 8 X 10 along the Gulf of Mexico coast to 12 X 10 in southern Canada in the units used on the charts. Therefore, in mid United States, an absolute vorticity of 10 X 10 sec" is close to the local value of the Coriolis Parameter (f) with a near zero relative vorticity. Absolute vorticity is determined and analyzed as follows: a. Height fields at seven sigma surfaces (see chart UP-2 and appendix 39) are computed from height and temperature fields at nine analyzed constant pressure surfaces and the tropopause . b. Heights at the sigma surfaces are unsmoothed to overcome truncation errors which result from the multi-step proce- dure used to compute the relative vorticity. The unsmooth- ing has the effect of amplifying the winds computed from the heights. c. Heights on the sigma surfaces are averaged to give the mean heights in the six sigma layers between (appendix 39). The balance equation is solved to give a mean stream func- tion field in these layers. i REFERENCE: 1. Shuman, F. G., "Numerical methods in weather prediction: I. The balance equation," Monthly Weather Review, Volume 85, October 1957 pp 329-332, d. Mean u- and v-components for these layers are computed from stream function fields by equations: dj_ SY U " dy V dx where Y is the stream function WBFH NO. J ISSUANCE 3-11 67-1 10-1-67 e. u- and v-components at 500 mb are interpolated assuming a linear variation with a function of pressure TT 1 . f . Absolute vorticity at 500 mb is computed by ■n = r + f = 2* -2H + f 1 b fcc oy at each grid point. Curve Follower A special computer program determines the x- and y-coordinates of loca- tion points 1/8" apart on the map scale along standard isopleths of the parameters by quadratic interpolation of the grid point values. The Curve Follower traces out the location points to draw the various isopleths. Depiction Contours are depicted by solid lines at 1) 60 meter intervals on 500 mb and 2) 120 meter intervals on 300 mb charts. Contours are hand-labeled by 3-digit numbers in decameters. Circulation centers are indicated by "L" for lows and "H" for highs. "H" and "L" symbols drawn by the Curve Follower always bear the same relation to the location of the actual center, as shown here: l± location of center Short-dashed lines depict 1) isotherms at intervals of 5°C so labeled on 500 mb charts and 2) isotachs at intervals of 20 kt up to 160 kts and intervals of 40 kt above 160 kt on 300 mb charts labeled in knots. Isopleths of absolute vorticity are depicted by solid lines at intervals -5 1 of 2 X 10 sec x hand-labeled as 2, 4, 6, etc. Centers of maximum and minimum vorticity may be marked by + with value indicated by the mul- tiple of 10" 6 sec -1 . X TT is the ratio of absolute temperature to potential temperature: e uooo/ Viooo/ WMH NO. I ISSUANCE 671 10-1-67 3-1Z • UA-3; upper-air analysis Hand-plotted and computer analyzed, Pacific and Atlantic Sections of Northern Hemisphere (see appendix 15) on a 1:20 million scale chart for 0000Z and 1200Z. Charts in this series are: 1. 700 mb contours and isotherms, Atlantic Section without data, Pacific Section with data. 2. 500 mb contours and isotherms, Atlantic and pacific Sections with data. (A preliminary and operational edition of this chart are sent). 3. 300 mb contours and isotachs, Atlantic and Pacific Sections with data. 4. 200 mb contours and isotachs, Atlantic Section without data, Pacific Section with data. Plotting Procedures 700 mb chart 1 . NETWORKS : On Pacific Section only , all island, OSV 1 and moving ship radiosonde and rawinsonde reports plus coastal North American, coastal Asian and all Alaskan radiosonde and rawinsonde re- ports available by 1/2 hours before transmission time are plotted. No AIREP data are plotted. Data are plotted on a 1:30 million base chart. 2. M3DEL: The plotting model (see appendix 9) follows the abbreviated WMO model for upper air data. 3 . DEADLINES : Plotting of data on the 1:30 million base chart stops at 1/2 hour before transmission time. The chart is then transferred to the Curve Follower which draws the computer analysis. The completed chart is then enlarged photographically to a 1:20 million scale for transmission. A check-list of key ocean observations used in the computer analysis appears on each chart. ■""Ocean Station Vessel 3-13 WBFH NO. 1 ISSUANCE 67-J 10147 500 mb chart NETWORKS : On the NMC hemispheric 1:20 million base chart are plotted all island, OSV and moving ship, and North American radiosonde and rawinsonde reports. Over Europe~and Asia, the reports are plotted for a network shown by circled stations in appendix 15. 2. MODEL: The plotting models used for radiosonde, reconnaissance and the criteria and model used for AIREP reports are shown in appendix 9. The radiosonde plotting model follows the ab- breviated WMO model for upper air data. DEADLINES : Data plotted on the NMC hemispheric 500 mb 1:20 million base chart are reproduced at 3 1/2 hours after observation time for the PRELIM analysis (1+30) and at about 5 hours after observa- tion time for the OPERATIONAL (3+25) analysis on a 1:30 million scale. The analyses are drawn by the Curve Follower and photo- enlarged to 1:20 million for transmission. A checklist of key ocean observations used in the computer analysis appears on each chart. 300 mb chart 1 . NETWORKS : On the Pacific Section only are plotted all island, OSV, and moving ship plus coastal North American, coastal Asian, and all Alaskan radiosonde and rawinsonde reports across the Pacific to 120° E longitude. Over Asia and Europe, the network shown in appendix 15 is used. 2. MODEL: The plotting models used for radiosonde, reconnaissance, and the criteria and model used for AIREP reports are shown in appendix 9. The radiosonde plotting model follows the ab- breviated WMO model for upper air data. 3. DEADLINES: All observations available by 1/2 hour before transmission time are plotted. Data are plotted on the 1:30 million base chart on which the computer analysis is drawn by the Curve Follower. This chart is enlarged photographically to a 1:20 million scale for transmission. A checklist of key ocean ob- servations used in the computer analysis appears on each chart. WBFH NO. 1 ISSUANCE 67-7 101-67 3-14 200 mb chart 1 . NETWORKS On Pacific Section only, all island, OSV and moving ship, plus coastal North American, Coastal Asian, and all Alaskan radio- sonde and rawinsonde reports are plotted. No AIREP or recon- naissance data are plotted. 2. MODEL: The plotting models used for radiosonde, reconnaissance and the criteria and model used for AIREP reports are shown in appendix 9. The radiosonde plotting model follows the ab- breviated WMO model for upper air data. 3 . DEADLINES : All reports available by 1/2 hour before transmission time are plotted on the 1:30 million base chart on which the computer analysis is drawn by the Curve Follower. This chart is en- larged photographically to a 1:20 million scale for transmis- sion. A checklist of key ocean observations used in the computer analysis appears on each chart. Computer Procedures The computer analysis proceeds as a separate operation from the hand- plotting already discussed. The analyses are based on ADP (automatic data processing) which begins at the following times: 1. 700 mb; 3 hours after observation time. 2. 500 mb; Preliminary, 1 1/2 hours after observation time, and Operational, 3 hours and 25 minutes after observation time. 3. 300 mb and 200 mb; 3 hours and 25 minutes after observation time. At these times, all data available in the storage facility of the NMC Communications Computer (IBM 360 System) are fed into the main NMC com- puter (IBM 7094). Then the ADP program decodes, hydrostatically checks, recomputes and lists all available radiosonde, rawinsonde, pibal recon- naissance and AIREP reports. Civilian AIREP reports, edited and coded at five Weather Bureau field offices are occasionally available for the analyses started at 3+25 hours after observation (see appendix 10). Approximately 75 military AIREP* s primarily over the ocean areas are also available to NMC for the analy- ses based on this data cut-off time from the USAF Computerized Flight Planning Section at Suitland. For a brief description see: WBFH NO. 1 ISSUANCE 3-15 67? JO-I-67 REFERENCES : 1. Burnett, F. W. , "The Role of the Computer in Meteorology", Weatherwise . Vol. 18 No. 5, October 1965. Computer Analysis Procedures Details of NMC*s complex and ever-changing computer analysis procedures will not be given here. The most recent references available on this subject are: REFERENCES : 1. Gustafson, A. F. , and McDonell, J. E., "The Derivation of First Guess Fields for Objective Analyses, 1000 mb to 500 mb", NMC Technical Memo #31, or 2. Kulawiec, M. H. , "The New Machine Analysis", Notes to Forecasters, May 1965. Philosophy of Analysis The most important points to understand when using computer analyses are: 1. Computer analyses are made from data derived at a network of grid points spaced about 180 nautical miles apart (see appen- dix 11). The positions of contours, isotherms, and isotachs drawn by the Curve Follower at NMC, are interpolated from values at points on this fixed grid. Systems with a wavelength (e.g., trough to trough) less than 200 nautical miles in ex- tent will not be evident on these analyses. Furthermore, smoothing during the computer analysis eliminates most "wiggles" or systems smaller than 400 nautical miles in extent. 2. The computer analysis involves two main procedures: a. Obtaining the best guess of values of parameters (height, temperature, etc.) from a short-range prognosis or by ex- trapolation with statistical regression equations from values of parameters already analyzed at other levels. Two references listed above, detail the method of obtaining the 500 guess field. The 300 mb and 200 mb guess fields are ob- tained as shown in appendix 12. b. Adjusting these guess values by a weighted average of the new data available in an influence area surrounding each grid point. The size of the influence area is controlled by the amount of data available. Over the United States this influence area averages about 400 nautical miles in radius. Over ocean areas, where observations are few and far between, a much larger (up to 1000 miles) influence area is searched before enough data for a new analysis are W§FM NO. J ISSUANCE 671 10-7^7 3-16 obtained. Often, over the Pacific Ocean, the guess field becomes the new analysis when no new data are available at any level. Computation of Parameters 1 . Contours and isotherms On all charts these are computed using the same ADP (automatic data processing) and analysis procedures described in the preceding paragraphs. 2. Isotachs Isotachs on the 300 and 200 mb analysis are based on a wind analy- sis which treats the geostrophic wind as a first-guess and adjusts this by the wind observations. Therefore, over areas with adequate coverage, the new wind data determine the isotachs by the same method and within the scale limitations already discussed for con- tour and isotherm analyses. Over sparse-data areas, the isotachs are based primarily on the geostropic wind derived from spacing of contours. Depiction Contours are depicted by solid lines at 1) 60 meter intervals on 700 mb and 500 mb charts and 2) 120 meter intervals on 300 mb and 200 mb charts Contours are hand labeled by 3-digit numbers in decameters. Circulation centers are indicated by "L" for lows and "H" for highs. The "H" symbol for a high center and the %" symbol for a low center, drawn by the Curve Follower, always bear the relation shown here to the location of the actual center. I±- •location of center Short dashed lines depict 1) isotherms at intervals of 5°C so labeled on 700 mb and 500 mb charts and 2) isotachs at intervals of 20 kt up to 160 knots and intervals of 40 kt above labeled in knots on 300 mb and 200 mb charts. WBFH NO. 1 ISSUANCE 3_17 67-1 101-67 UA-3A; 850 MB ANALYSIS Computer analyzed for Pacific Section of the Northern Hemis- phere (see appendix 15) on a 1:30 million scale for 0000Z and 1200Z. The analysis includes contours and isotherms without plotted data. Computer Procedures The ADP (automatic data processing) and analysis procedures begin 1 1/2 hours after observation time and are similar to those discussed in Chart UA-3 for the 500 mb analysis. Height and temperature analyses are made from data derived at a network of grid points spaced about 180 nautical miles apart. The positions of contours, isotherms and low and high centers are interpolated from the grid point data and drawn bv the Curve Follower. Solid lines at 60 meter intervals (30 meter June 15-0ctober 1) are used for contours, hand labeled in decameters. Isotherms are dashed lines at 5° C intervals so labeled. The "H" and "L" symbols, drawn by the Curve Follower, always bear the relation shown here to the actual location of the pressure center. 1+ ■location of center WBFH NO. I ISSUANCE 3-19 67.1 101-67 UA-4; UPPER AIR ANALYSIS 500 mb computer analysis without data for the Northern Hemisphere on a 1:40 million scale for 0000Z only. Includes contours with jet cores drawn by hand. Description The analysis is a photo-reduction from the computer analysis on a 1:30 million scale of data available up to 3 + 25 hours after observation time of 0000Z. The automatic data processing (ADP) and analysis pro- cedures used in preparation of this analysis are the same as those described under chart UA-2. Isotachs analyzed by the computer are used as guidance in locating the jet cores. Depiction Contours are drawn as solid lines at 60 meter intervals hand-labeled in decameters. High and low centers are printed out with the conven- tion illustrated under chart UA-2. The jet core is portrayed by heavy arrows . WBFH NO. I ISSUANCE 3-21 671 10-1-67 UA-5; THICKNESS ANALYSIS 1000-500 mb computer analyzed for 0000Z and 1200Z, as follows: a. United States Section at 1:20 million scale, with computer surface analysis, both based on data avail- able at 1 1/2 hours after observation time, transmit- ted without data. b. Atlantic and Pacific Sections at 1:20 million scale (see appendix 15) with data computed and plotted by hand. Plotting Procedures Atlantic and Pacific Sections: 1 . NETWORKS : All island, OSV, moving ship, and coastal radiosonde and rawinsonde reports are plotted. 2. MDDEL: The plotting models used for radiosonde, rawinsonde and recon- naissance reports and the criteria and model used for AIREP reports are shown in appendix 9. The radiosonde plotting model follows the abbreviated WMO model for upper air data. 3 . DEADLINES : All reports available by 1/2 hour before transmission time are plotted on a 1:30 million scale. 4 . PREPARATION : The following procedures are used for hand computation and plotting of the 1000-500 mb thickness data and thermal winds. a. Thickness values are determined by subtraction of re- ported or computed 1000 mb heights from reported 500 mb heights. b. Thermal winds are computed by vector subtraction of geostrophically measured sea level winds from reported 500 mb (or 18,000 ft) winds. (Geostrophic sea level winds are determined: by measuring spacing and direc- tion of isobars on Chart SA-1 for land stations; and by veering surface wind direction 15° and multiplying velocity by 1.4 for ship reports.) WBFH NO. ? ISSUANCE 3-23 67-1 101-67 Computer Procedures; ADP The automatic data processing which begins 1 1/2 hours after observa- tion time first objectively determines values of sea level pressure and temperature at each grid point of the NMC grid (appendix 11). The pro- cedure uses values of pressure determined from the 12-hour surface fore- cast and values of temperature derived from the 12-hour thickness fore- cast, both verifying at the time of the analysis, as the first guess fields. These values are corrected for available surface observational data to' give objective sea level pressure and temperature data for the analysis at each grid point. The program hydrostatically derives 1000 mb heights from these data. This 1000 mb field is further modified by available observed 1000 mb heights and by "bogus" data manufactured from subjective surface analyses in areas where no real data are available. 500 mb heights at the grid points are determined as described for Charts UA-2,3. Thickness values at each grid point are computed by sim- ple substraction of 1000 mb heights from 500 mb heights. Computer Analysis Procedures The ADP program determines sets of x- and y-coordinates for isobars and thickness isopleths by quadratic interpolation from the grid point' values of sea level pressure and thickness respectively. The Curve Fol- lower traces out the lines from the coordinates on a 1:30 million scale. The charts are photo-enlarged to a 1:20 million scale for transmission. Depict ion United States Section Surface isobars are depicted by solid lines at 8 mb intervals (4 mb intervals June 15-October 1) labeled by hand by 2-digit num- bers, units and tens of pressure in millibars. High and low cen- ters are indicated by convention for numerical analyses described for chart UA-2. Thickness isopleths are drawn as dashed lines labeled in decameters. Atlantic and Pacific Sections Thickness isopleths are depicted by solid lines labeled in decameters. W$FH NO. J ISSUANCE 47-1 J 0-1 -67 3-24 UA-6; TROPO PAUSE AND WIND-SHEAR ANALYSIS Analyzed by computer in a 2-panel presentation for the 48 states of the United States, southern Canada, northern Mexico and the contiguous ocean areas on 1:20 million scale for 0000Z and 1200Z. Analysis Procedures The initialization procedure for the 6-layer numerical prediction model begins 3+25 hours after observation time. After the analysis of height and temperature at the 10 constant pressure surfaces has been completed, the pressure and temperature of the tropopause are determined semi-ob- jectively by a technique developed by Gustafson. REFERENCES : 1. Gustafson, A. F. , "Objective Isentropic Analysis," NMC Technical Memorandum No. 30, Washington, D. C.,1964. 2. Gustafson, A. F. , "Objective Analysis of the Tropopause',' NMC Technical Memorandum No. 33, Washington, D. C.,1965. The initialization process computes the pressure and height of the tropopause and other cr-surfaces; and mean u- and v- components of the wind in the layers between the a-surfaces of the 6-layer numerical pre- diction model (see appendix 39) at each grid point spaced about 180 nau- tical miles apart (see appendix 11). The mean layer winds are assumed to to apply at the midpoints of the layers. The heights of the midpoints are determined by averaging the heights of the bounding a-surfaces. The maximum wind at the tropopause is computed from the formula: V m ax = 1/2 (v 3 + V 3 ) + 1/4 (% - V x ) + 1/4 (? 3 - V 4 ) where V is the mean scalar wind [^ \ u 2 + v 2 ) in the layer indicated by the subscript (appendix 39). The average scalar wind-shear is computed using the formula: v max - Vi + v max - V 4 Wind-shear = l/2 Z max " h Z max " \ where Z max is the height of the maximum wind or tropopause and Z is the mean height in the layer indicated by the subscript (appendix 39). The numerical analysis procedure duplicates as closely as possible the manual analysis procedure which was once used. The technique presumes WBFH NO. I ISSUANCE 3-25 67-1 10-1-67 a smoothed wind speed profile with the following characteristics: 1. One maximum wind level. 2. Shears of equal magnitude above and below the level of maximum wind. 3. The maximum wind is at the analyzed tropopause height. (The maximum wind will be at or close to the reported tropopause height at middle and high latitudes. Frequently it will be associated only with a weak stabilization or inversion layer which does not meet the WMO tropopause definition at lower latitudes. The objective analysis procedure places the tropo- pause at the level of the maximum wind in these areas.) 4. The direction of the wind is constant with height. 5. The smoothed wind field is fitted as closely as possible to the analyzed wind speeds by the computation equations. The computer program forms stream functions at each grid point from the u- and v-components of the maximum wind at the tropopause level. By these procedures, the program has computed the following parameters at each grid point: 1. The pressure and height of the tropopause-maximum wind level. 2. The maximum wind speed at the tropopause. 3. The magnitude of the average absolute wind shear from about 10,000 feet above to about 13,000 feet below the tropopause- maximum wind level. 4. The stream function at the tropopause-maximum wind level. Depiction x, y-coordinates for points along isopleths for standard values of the various parameters are determined by the computer analysis program. The Curve Follower traces out these points to form lines representing the analyses of the parameters. These analyses are depicted in two panels on a standard 12" X 18" facsimile chart. The upper panel contains: 1. Isopleths of stream functions depicted by solid lines with ar- row barbs indicating direction of flow added by hand. These are parallel to the direction of the maximum wind at the tropo- pause level with spacing governed by the speed of the maximum wind (equivalent to 120 meter spacing of contours). W&FH NO. J ISSUANCE 67-7 10-1-67 3-26 % % 2. Isotachs of maximum wind speed depicted as short-dashed lines at 20 knot intervals labeled by hand. 3. The axis of the jet core depicted as long-dashed heavy line with arrowheads, hand-drawn through the centers of the isotach maxima. The lower panel contains: 1. Isopleths of the height of the tropopause-maximum wind level depicted as solid lines hand-labeled in feet. The contours actually are the intersections of the tropopause with the standard constant pressure surfaces: 150, 200, 250, 300, 400, and 500 mb. The pressures are equated to the reference heights of a standard atmosphere at each constant pressure surface. The labeled heights therefore will be too high where the D-values for the intersections are negative and too low where the D-values are positive. 2. Isopleths of average vertical wind- shear depicted as short- dashed lines hand-labeled in knots per 1000 feet, for each 2 knots of shear. WBFH NO. 1 ISSUANCE 5 ~ Z7 671 10-1-67 U A -7- UPPER- AIR ANALYSES - MIA Hand plotted and analyzed for 0000Z and 1200Z on a 1:20 million scale Mercator projection. The 200 mb chart covers the area from 150 W to 20 E longitude and from 40 S to 45 N latitude. The 850 mb, 700 mb, 500 mb, and 300 mb charts are for the area 120 W to 20 W longitude and 10 S to 45 N latitude. (See appendix 52.) The 850 mb, 700 mb, and 300 mb are transmitted with data only. Plotting Procedures 1 . NETWORKS : All available radiosonde, rawindsonde, pibal, and weather recon- naissance reports and AIREPS are plotted. The models of appen- dix 9 are used except that all AIREPS are entered on the map nearest in time and in height to the report. Reports are entered as received. Reports that appear questionable are checked for ac- curacy of entry, internal consistency, location, etc. 2. MODELS: Station models used are shown in appendix 9. 3 . DEADLINES : There is no hard cut-off time for data entry and analysis except that imposed by the facsimile transmission schedule. Deadline for entry of data which is normally considered in the analysis is 30 minutes before transmission time. Analysis Procedures 1. TIME AVAILABLE: One analyst works on each chart and completes it in approximately one hour by direct analysis of the data. The 500 mb chart is completed about 6 1/2 hours and the 200 mb chart is completed about 7 hours after observation time. 2. TOOLS AVAILABLE: a. NMC mid-latitude and experimental tropical model analysis for comparison and interpretation. b. Continuity. c. Current surface analysis. d. Satellite observations. These have become an essential aid to analysis of the upper level contour charts. Where low WBFH NO. ? ISSUANCE 3_29 67-1 10-1-67 level cloud patterns can be identified, inferences can be drawn concerning low troposphere wind direction, areas of very light winds, and position of ridge lines. Where high level cloud patterns can be identified, inferences can be drawn concerning wind direction, jet stream cores, high level ridges and cold low positions. (The Operations Office (NESC) makes "high troposphere" wind estimates that are transmitted on the South Atlantic coastal facsimile circuit as charts 2401 and 2444.) e. Mean monthly charts for the tropics. REFERENCES : On Jet Streams: Whitney, L. F., Timchalk, A., and Gray, T. I., Jr., "On Locating Jet Streams From Tiros Photographs", Monthly Weather Review , Vol. 94, No. 3, March 1966, pp 127-138. On Blow-Offs: Erickson, Carl 0., "Satellite Photographs of Convective Clouds and Their Relation to the Vertical Wind Shear", Monthly Weather Review , Vol. 92, No. 6, June 1964, pp 283-296. On Cold Core Cyclones: Frank, Neil L., "The Weather Distribution With Upper Tropospheric Cold Lows in the Tropics", Southern Region Technical Memorandum No. 28, U. S. Weather Bureau, ESSA, September 1966, 6 pages. On Monthly Mean Charts: Heastie, H., and Stephenson, P. M. , "Upper Winds of the World (Parts 1 and 2)," Geophysical Memoirs No. 103 , British Meteorological Office, London, 1960, 217 pages. Philosophy of Analysis The basic purpose of the charts is to present a meaningful analysis of wind flow and temperature patterns over the area. To this end: 1. Streamlines are drawn over the area between 20°N and 20° S and contours are drawn poleward of 20°N and 20°S. 2. When it is felt that standard contours do not adequately depict the wind flow in a particular area, intermediate contours and/or streamlines are added or extended poleward of 20°N and 20°S. WBFH NO. J ISSUANCE 67-1 10-1-67 3-30 3. Where contour heights and wind reports appear inconsistent, priority consideration is given to the winds unless several reports in the same general area indicate a definite ageostrophic flow. 4. Over sparse data areas there is a heavy reliance on aircraft wind reports. 5. Consistency between levels becomes an important analysis tool in sparse data areas, especially in view of item no. 4 above. This is particularly true of the 200-mb and 300-mb levels. 6. An underlying concept for analysis at low latitudes is to model the atmosphere in terms of a lower portion and a higher portion, each with characteristic disturbances. These layers and disturbances appear to behave independently of one another a large part of the time, although they may interact. In this sense, the TOE chart and the 200-mb chart characterize their respective layers, and the intermediate level charts provide information on the transition between the two. Depiction Sixty meter contours are analyzed at 500-mb and 120- meter contours at 200 mb poleward from 20 N. and 20 S. and are blended into a streamline analysis between 20 N« and 20 S. Isotherms are drawn for 5-degree intervals and isotachs for 40- knot intervals beginning at a base of 20 knots. Centers of cyclonic circulation are labeled "l" and those of anticyclonic with an "H". On the 850-mb, 700-mb, and 300-mb charts, only the plotted data are entered. WBFH NO. ? ISSUANCE 3-31 671 10-1-67 _, AC-1; TWELVE-HOUR SURFACE PRESSURE- CHANGE ANALYSIS Corrected for diurnal variation, issued daily for 0000Z, plus-each-6-hours for North America and surrounding ocean areas on a 1:30 million scale. Charts for 0000Z and 1200Z produced on the computer from data available at 1+30 hours after observation; charts for 0600Z and 1800Z are made from hand analysis. Hand Analysis Procedures (0600Z, 1800Z) 1. TIME AVAILABLE: 45 minutes are used for plotting and 45 minutes are used for analy- sis of the charts. 2. PREPARATION: These analyses are plotted, analyzed and traced by hand. Only standard synoptic reporting stations (i.e., SM* s) are used over North America. The procedures followed in making the analysis are: a. Plotting and subtraction of two pressures, for analysis time and for 12 hours earlier, reported at SM stations on a 1:20 million base chart. b Addition (with proper sign) of 12 hour diurnal changes de- rived from Weather Bureau Technical Paper No. 1, "Normal Pressures and Tendencies for the United States", Washington 1943. c. Analysis of centers of maximum change and isal lobars from pressure changes over North America. Over ocean areas, the isopleths are determined by graphical subtraction of the corresponding North American analyses (Chart SA-1). This analysis is performed by an Analyst Assistant, and checked by the Guidance Forecaster doing the surface prognosis* d. Photo-reduction of manuscript analysis to 1:30 million scale. e. Tracing and labelling of isopleths and centers on the fac- simile base chart. WtFH NO. ? ISSUANCE 4-1 671 10-1-67 Computer Analysis Procedures The analyses for 0000Z and 1200Z are computer produced but traced by hand for transmission. The change is between pressures from the objec- tive surface analysis made 1 1/2 hours after the current observation time (end of period) and 8 hours after the observation time 12 hours earlier (beginning of period). The ADP (automatic data processing) and surface analysis procedures are discussed under Chart UA-5. The proce- dures followed in making the analysis are: a. Subtraction in the computer of the analyzed pressures at the beginning from those at the end of period at each NWP grid point (see network in appendix 11) and, b. Addition, with proper regard for sign of the normal diurnal variation at each grid point. The normals have been obtained from 16 years (1950-65) of surface data available in the Extended Forecast Division of NMC. c. Interpolation of centers of greatest pressure-change plus isopleths of 4 mb changes (zero, + 4, etc.) from grid point data. Isopleths and central values are drawn on NMC* s Curve Follower. d. Tracing and labelling of these isopleths and centers on the facsimile base chart are done by hand. Depiction , Zero changes are drawn as heavy-solid lines, positive changes as light- solid lines and negative changes as light-dashed lines. Isallobars at 4 mb intervals are labeled in millibars of change with proper sign. Centers of maximum change are indicated by the appropriate sign of the change. When available, smoothed tracks of four past positions are entered on the chart. W&FH NO. I ISSUANCE 671 10-1-67 ^~ 2 AC-2; 500 MB 24-HOUR HEIGHT CHANGE ANALYSIS Produced on the computer from data available at 1 1/2 hours after observation time on 1:30 million scale for North American area for 0000Z and 1200Z. Computer Procedures This change chart is the difference between two 500 mb analyses. The analysis at the beginning of the 24-hour period is based on a data cut-off 8 hours after observation time. The current analysis is based on data available at 1 1/2 hours after observation time. Therefore, each succeeding change chart is based on latest version of the earlier analysis. However, there is seldom a significant difference between 1 1/2 and 8-hour analyses over North America since most data are avail- able by 1 1/2 hours after observation. The 500 mb height differences are computed at a network of grid points spaced about 180 nautical miles apart (see appendix 11). The facsimile charts of the height-change analysis drawn by the automatic Curve Follower are interpolated from change values on this fixed grid. Limitations of the Curve Follower equipment restrict drawing of lines (e.g., circular centers) to those 2 inches or more in length, measured on a 1:30 million chart. Therefore, the central 60-meter change-contour will be omitted when the circum- ference of the central contour is less than 2 inches. The 500 mb analy- ses on which the change chart is based are made using the general Com- puter Analysis Procedure described under Chart UA-2. Depiction Isallohypses are depicted as solid lines at 60 meters of change inter- vals hand labeled with appropriate sign in decameters of change. Cen- ters of maximum change and values in decameters are printed by the Curve Follower. 12-hourly past position tracks of centers are added by hand. WBFH NO. ? ISSUANCE 4_3 67-1 101-67 AC-3; COMPOSITE MOISTURE index chart 4 panels at 1:25 million scale, each for United States, southern Canada and northern Mexico; containing the fol- lowing information plotted and analyzed by hand: a. Showalter stability index analysis b. Lowest freezing level analysis c« Precipitable water analysis, surface to 500 mb d. Average relative humidity analysis, surface to 500 mb Plotting Procedures 1 . NETWORKS : All radiosonde reporting stations in United States, southern Canada, and northern Mexico are used if they are available by 3 1/2 hours after data tj.me for charts a and b, and 3 hours after data time for charts c and d (see above). 2. SOURCES: a. Stability indices are plotted from the early RADAT, or UKUS transmissions. If data are missing, the index is computed by hand from the radiosonde report when it is received at NMC. b. Freezing level heights are plotted, from the 0100Z and 1300Z airway reports (AW). If data are missing, a computation of the freezing-level heights made on the NMC computer is used (see description of method which follows). c. Precipitable water and average relative humidity data are plotted from listings made up on the NMC computer at 3 hours after data time (see description of methods which follow). Analysis Procedures 1. TIME AVAILABLE: About 30 minutes are available for the analyses of the charts. 2 . PROCEDURES : All 4 analyses are performed on the synoptic scale as defined by the network of available upper-air soundings. Care is taken to WBFH NO. J ISSUANCE 4„5 67-1 10-1-67 maintain continuity of pattern from one chart to the next and consistency with latest surface analysis. 1. Isopleths of stability index are analyzed for intervals of 4 units. Areas of index values less than + 4 are labelled unstable (U). Areas of high index values (above + 4) are labelled stable (S). 2. Although several freezing levels may occur on a sounding, and are plotted on the chart, only the lowest freezing level is analyzed. The surface intersection (32° F) is drawn as a dashed line, and the free-air contours are drawn as solid lines for 4,000 foot intervals. The free-air contours are shown as discontinuous where they intersect smoothed terrain contours in the western United States. 3. The precipitable water is analyzed for intervals of .50" with .25" (dashed)isopleths used to define the pattern when necessary. 4. The relative humidity is analyzed for intervals of 10% for humidities 50% and higher. REFERENCES : 1. STAFF, A&FD, NAWAC Manual, Part I. pp. 30-45. 2. Showalter, A. K., "A Stability Index for Thunderstorm Forecasting", Bulletin American Meteorological Societ y. 1953. Vol. 34, pp 250-252. Computation of Parameters 1. FREEZING LEVEL DATA First, the pressure of the freezing level is calculated by loga- rithmic interpolation from the pressure levels reporting tempera- tures on either side of zero. Next, the height of the freezing level pressure is calculated from heights at the standard pressure levels (e.g., 850 mb, 700 mb, etc.) by logarithmic interpolation or extrapolation, whichever is necessary. 2. PRECIPITABLE WATER (SURFACE TO 500 MB) The precipitable water is computed from the temperature and dew- point values at each point on the sounding. The precipitable water observation shown on the chart is the sum of the individual pres- sure weighted precipitable water values for each sub-layer defined by temperature-dewpoint observations on the sounding. Thus: 500 W p = S (.0004 r dp) where sf c WBFH NO. I ISSUMKt «M I0-M7 4-6 C r = « 625e and p - e Wp is the total precipitable water from surface to 500 mb dp is the pressure difference between top and bottom of each sub- layer r is the average mixing ratio of the sub-layer (dp) e is the average vapor pressure of the sub-layer (dp) and is calculated by the method given in the Smithsonian Tables pp. 347-374. p is the average pressure of the sub-layer (dp) The hand method used previously is described in appendix 40. REFERENCES : 1. STAFF, A&FD, NAWAC Manual , Part I, p. 30. 2. Solot, S. B., "Computation of Depth of Precipitable Water in a Column of Air", Monthly Weather Review , April 1939, pp. 100-103. 3. AVERAGE RELATIVE HUMIDITY (SURFACE TO 500 MB) The relative humidity values are computed first for each sub-layer, weighted by the pressure depth of the sub-layer, summed and pres- sure averaged over the layer between surface and 500 mb. Thus: 500 E ( h ) dp H = — where DP h = 100 _£_ (£ n percent) and E H is the average relative humidity in the layer surface to 500 mb (DP) h is the average relative humidity in each sub-layer (dp) where e" is the average vapor pressure (computed by the method in the Smithsonian Tables pp. 347-374) and E is the average saturation vapor pressure for the sub-layer. WBFH NO. J ISSUAKl 4_ 7 47-1 101-67 <■ • m AC-4; MAXIMUM AND MINIMUM TEMPERATURE CHARTS Hand-plotted for temperatures observed during the 12 hours ending at 0000Z and 1200Z, respectively, at 1:12.5 million for the United States area only. Plotting Procedures 1 . NETWORKS : Station circles for the network used are "blacked in" on the base chart. A map of the network stations, with identifiers, is given in appendix 26* Sources for data are the SM* s on Service C with fill-ins from the aviation observations on Service A. 2 . MODELS : When both a city office and an airport office send temperatures, the city office temperature is plotted on-station and the airport temperature is listed in a printed box, labelled AIRPORT TEMP, on the right hand edge of the chart. The RECORD TEMPS box printed in the Gulf of Mexico is filled in from the fifth group of the SM (Hi-Lo report) for all records reported on each set of data. Contraction Type of Temperature Record HIXFM Highest exceeded For the Month LOXFM LOwest exceeded For the Month HIEFM Highest Equaled For the Month LOEFM LOwest Equaled For the Month Spring temperatures, March, April, and May HIXSE Highest exceeded So Early LOXSL LOwest exceeded So Late HIESE Highest Equaled So Early LOESL LOwest Equaled So Late Autumn temperatures, September, October, and November HIXSL Highest exceeded So Late LOXSE LOwest exceeded So Early HIESL Highest Equaled So Late LOESE LOwest Equaled So Early WBFH NO. J ISSUANCE 4-9 67-7 10-1-67 All time records, (since observations began) HIXAT LOXAT HI EAT LOEAT Highest exceeded for All Time LOwest exceeded for All Time Highest Equaled for All Time LOwest Equaled for All Time « 3. DEADLINES: All data available by 5 minutes before transmission time can be plotted on the chart. WtFH no. 1 671 ISSUANCE 10-1-67 4-10 AC-5; OBSERVED 24-HOUR PRECIPITATION AMOUNTS ( INCLUDING TRACES ) Plotted by hand on a 1:12.5 million base for the United States, southern Canada, and northern Mexico, once-per-day at 1200Z. The chart is transmitted at 1415Z on the Forecast Center Facsimile Circuit and at 1532Z on the National Facsimile Chart. Plotting Procedures 1. NETWORKS: All available stations are plotted. Sources are 1200Z SM' s on Service C, 1200 AW s on Service A, and SR* s on Service C and RAWARC. Also, 6 hourly precipitation observations are used to plot traces. 2 . MODELS : All observations that space allows are plotted in hundredths of an inch on the base chart. Additional reports, which can't be fitted on the base chart are plotted in a special column form, printed on the right side of the chart, 3. DEADLINES: Data can be plotted on the chart until about 5 minutes before transmission time. This chart is transmitted twice; first, at 1415Z (on the Forecast Center Facsimile Circuit) when only the basic network of synoptic (SM) and aviation (AW) observations are available, and later at 1532Z on the National Facsimile Circuit when more observations from hydrologic stations (SR* s) have been received. WBFH NO. J ISSUANCE 4-11- 67-1 J0-7-67 § AC-6; OBSERVED SNOW COVER CHART Plotted by hand, four times per day. a. At 0000Z and 1200Z, on a 1:20 million base for the United States area. b. At 0600Z and 1800Z, on a 1:25 million base chart in the lower right panel of the Upper Level Winds Aloft Chart (AC-7) . Plotting Procedures 1. NETWORKS: All available stations are plotted. The 1200Z chart contains the greatest number of observations, since most stations report the depth on the ground at that time. At 0000Z, only those stations reporting precipitation during the past 6 hours, report snow depths. Water equivalents are usually reported only on Tuesdays and Thursdays. NMC seldom receives many 0600Z and 1800Z snow depth reports. 2 . MODELS : The plotting model used on all four charts is: total snow depth ( ( 6 hr snowfall water equivalent ) 3. DEADLINES: All snow accumulation or snow depth reports available by 5 minutes before start of transmission are used. 4-13 WBFH NO. 1 67-1 ISSUANCE 1 0-1-67 AC-7; WINDS ALOFT AND TROPOPAUSE CHART Hand-plotted from observations at 0000Z plus-each-6 hours. The data are presented in the following 3 charts, each containing four 1:25 million panels of the United States, southern Canada and northern Mexico: a. Low Levels, Winds Aloft , containing 2nd standard level above surface (gradient), 850 mb, 8,000 foot, and 700 mb winds. b. Intermediate Levels, Winds Aloft , containing 14,000 foot, 20,000 foot, 25,000 foot, and 300 mb winds . c. Upper-Levels, Winds Aloft , containing 35,000 foot, 200 mb, and 50,000 foot winds. At 0000Z and 1200Z, the fourth panel contains tropopause data. At 0600Z and 1800Z, the fourth panel contains 6-hour snowfall amounts (see AC-6 for a description of this chart). Also at 0600Z and 1800Z the mandatory-level heights, temperatures and dewpoints from the United States stations taking intermediate radiosonde observa- tions are plotted on the 5,000 foot (850 mb), 10,000 foot (700 mb), 20,000 foot (500 mb), and 30,000 foot (300 mb) panels. Plotting Procedures 1 . NETWORKS : All available data from the upper-air network over the United States and southern Canada are plotted. The observations at OSV's November and Papa, and at Bermuda are inserted of f-position in special boxes along the edges of each chart. The basic source for United States upper-wind data are the UJ and UC collectives on Service C. In case of missing reports, the east coast Hurri- cane Circuit (when in service), and the RAWARC circuit, are checked for late transmissions. Canadian wind data are available at NMC on a special Suitland-Dorval Circuit and on Service Circuits. 2 . MODELS : The plotting model used is an abbreviated (wind only) version of the model shown in appendix 9. The height, wind, and temperature at the tropopause are obtained from the coded tropopause information WSFH NO. ? ISSUANCE 4-15 67 ., JO-1-67 in the radiosonde report. Heights are converted from meters to feet. The plotting model used is the same as that used for con- stant pressure charts and is shown in appendix 9. This same model is used for plotting mandatory level information when available at 0600Z and 1800Z. 3 . DEADLINES : The data are plotted until 5 minutes before transmission begins on the first Winds Aloft Chart. WBFH NO. I ISSUANCE 67-1 10-1-67 4-16 SP-1; NWP SURFACE PROGNOSIS Computer produced 24- and 36-hour objective sea level pres- sure prognoses, twice a day from 0000Z and 1200Z initial observations, covering the NMC Front Half section of the Northern Hemisphere (see appendix 14) on a 1:30 million scale. Transmitted with corresponding 1000-500 mb thickness prognoses superimposed. 1, Numerical Models . The sea level pressure forecasts are derived from the objective 1000 mb prognoses produced by the 6-Layer (PE) Numerical Prediction Model, which is the operational model at NMC. The Reed model, based on the 3-Level Baroclinic Model, is run as backup when the PE model fails. PE and 3-level models are described under Chapter 6, Chart UP-2. 1.1 The 6-Layer (PE) Numerical Prediction Model . The 1000 mb prognosis is a part of the comprehensive prediction package produced by the PE opera- tional forecast run which begins three hours and twenty-five minutes after observation time. 1.1.1 Computer Forecast Procedures . At the initial and forecast output times, the PE model provides pressures and heights on the a-surfaces and mean potential temperatures in the a-layers (see appendix 39) at each grid point of the NWP grid (see appendix 11). The lowest er-surface in the PE model is the surface of the earth. 1000 mb heights, initial and forecast, are deter- mined as follows: a. The mean potential temperatures in the boundary layer and the lowest tropospheric layer are extrapolated to the layer between the surface of the earth and the 1000 mb surface, assuming a linear variation with TT, a function of pressure (the Exner function): R TT = UU C P U0O0/ b. The difference in height between the surface of the earth and the 1000 mb surface is computed from the pressure difference and mean potential temperature in this layer by means of the hydro- static equation. Application of the height difference to the given height of the earth's surface (see appendix 17) determines the 1000 mb height at each grid point. c. The difference between the 1000 mb heights computed for the initial time and at the forecast output time represents the fore- cast 1000 mb height tendency. This tendency is added to the analyzed 1000 mb grid point height derived entirely from the objec- tive sea level pressure analysis produced as a part of the initial- ization procedure for the PE model (see Chart UP-2) to give the forecast 1000 mb heights at each grid point. WBFH NO. I R-7-J-68 5-1 1.1.2 Philosophy of Prognosis . The tendency technique produces a 1000 mb height field which reflects the pressure reduction procedures used in the ob- servational program rather than those used in the PE model. In mountain areas where the 1000 mb surface is often below ground level, the PE model tempera- tures extrapolated to the layer between earth' s surface and 1000 mb are con- sistently too warm. Consequently, 1000 mb heights computed using these tem- peratures are usually lower than those computed from observed radiosonde data. The tendency technique effectively eliminates this result of the pres- sure reduction procedure and produces forecast 1000 mb height fields which resemble those analyzed from observed data. 1.1.3 Computation of Parameters . The PE model numerical prediction run provides forecasts of 500 mb height at each grid point at output times. Sub- traction of 1000 mb from 500 mb heights produces the 1000-500 mb thickness forecast at each grid point. The 1000 mb heights are converted to sea level pressures p by this approxi- mate formula: (2 RT + g z where R = gas constant and T is an estimate of the 1000 mb temperatures given by: T = 14.3 (°C) + 0.0005266 &4° ° 00 where AZiooo *- s tne 1000 mb to 500 mb thickness (in cm). 1.2 The Reed Model . This simple 2-level barotropic vorticity model was developed by Dr. Richard J. Reed of the University of Washington to incor- porate the skill of the barotropic or baroclinic 500 mb numerical forecasts into numerical 1000 mb prognosis. 1.2.1 The Prediction Equation . The equation states a simple conservation principle : azo-zo+bzsj = (a zj - Zq + b z g where the subscript "f" stands for forecast time and "u" for upstream point; (a z - z ) is proportional to the 1000 mb vorticity and b Zg is proportional to the 500 mb height. The equation states that the value of the conservation function at any grid point is predicted to be the same as that at the up- stream end of a trajectory, determined by an "equivalent advecting wind field", terminating at the grid point in question. 1.2.2 Computer Forecast Procedures . The computer program uses the fol- lowing data available at each grid point of the NWP grid (see appendix 11): a. 1000 mb and 500 mb initial heights. ~ WtFH NO. 1 R-7-1-68 5-2 b. Forecast 500 mb heights at each hourly time step out to 48 hours from the 3-level baroclinic model forecast (see UP-2). The procedure begins with the 12-hour 500 mb forecast. At each grid point: a. A 12-hour trajectory is constructed upstream (back in time) using approximately 55% of the geostrophic 500 mb flow determined from the 500 mb height field at each hourly time step. These give the location points of the initial 1000 mb heights which will ar- rive at each grid point after the first 12-hour period of the forecast. b. One-half of the prognostic 500 mb height change along the tra- jectory (between the initial and terminal points) is added to the 1000 mb height advected to each grid point. This procedure results in a set of 12-hour prognostic 1000 mb heights for each grid point. The forecast computation then transfers to the 24-hour 500 mb prognosis. The same procedure constructs trajectories upstream to points for which 1000 mb heights may be interpolated from the 12-hour forecast grid point values. Half of the 500 mb height change along the twelve to twenty-four hour tra- jectory is added to give the 24-hour forecast 1000 mb heights at each grid point. The process is repeated for the 36- and 48-hour forecasts. 1.2.3 Philosophy of Forecast . The Reed Model operates on the principle that changes in the layer between 1000 mb and 500 mb result from simple horizontal advection. The conservation equation states that when the 1000 mb vorticity (circulation) increases during the forecast, the 500 mb heights decrease, and vice versa. The model contains a factor which is introduced to take account of terrain effects on both the wind flow and vertical motion. The term is not adequate in the areas of large mountains as well as those areas influenced by their proximity. The forecasts are poorest in these regions. 1.2.4 Computation of Parameters . The Reed model provides forecasts of 1000 mb height at each grid point for output times; the 3-Level Baroclinic Model, the 500 mb heights for the corresponding times. a. Subtraction of 1000 mb height from 500 mb height gives the 1000-500 mb thickness forecast at each grid point. b. 1000 mb heights are converted to sea level pressures at each grid point by the same procedure as that used in the PE model. 2. References . a. Reed, R. J., "Experiments in 1000 Mb Prognosis", Technical Memorandum No. 26, National Meteorological Center, U. S. Depart- ment of Commerce, Weather Bureau, 1963. 5_3 WIFH NO. 1 R-7-1-68 b. Reed, R. J., "On the Practical Use of Graphical Prediction v Methods", Monthly Weather Review , Vol. 88, No. 6, June 1960, pp 209-218. c. Roberts, C. F. , "Present and Future Operational Prediction Models", ESSA Technical Note 16-Fcst-3, October 1965. d. Shuman, F. G. , and J. B. Hovermale, "An Operational Six-Layer Primitive Equation Model", Journal of Applied Meteorology , Vol. 7, No. 4, August 1968. e. Technical Procedures Bulletin No. 7; "Sea-Level Pressure Forecasts from 6-Layer (PE) Numerical Prediction Model", Technical Procedures Branch, ESSA, Weather Bureau, September 1967. 3. Derivation of Output . A data processor on the IBM 7094II computer determines the x- and y-coordinates of closely spaced location points along standard isobars and thickness isopleths by quadratic interpolation from the grid point values of sea level pressure and 1000-500 mb thickness. The Curve Follower traces out the location points to draw the analyses for the forecast output times. 3.1 Depiction . The isopleths are depicted as follows: a. Isobars are drawn as solid lines at 8 mb intervals with inter- mediate isobars occasionally drawn as long-dashed lines at 4 mb intervals in areas of weak pressure gradient. (Solid lines at 4 mb intervals are drawn routinely June 15 - October 1.) Isobars are hand labeled by 2-digit numbers, tens and units of pressure in millibars. Positions of low and high centers are plotted by the Curve Follower in the standard way: position of centers These may be labeled by 3-digit numbers, in millibars with thou- sands digit omitted. b. Thickness isopleths are drawn as short dashed lines at 60 meter intervals, hand labeled in decameters. Centers of warm and cold pools may be indicated by + labeled in decameters. : " WBFH NO. 1 R-7-J-68 5_4 Derivation The 50O-mb prognoses used in this forecast are based on the 3-level baroclinic model run from the same set of initial data as described under chart UP- 2. The Reed model computes a forecast of 1000-mb heights at the network of grid points shown in appendix 11. The thickness forecast at each grid point is found by subtracting the Reed 100O-mb height from the 500-mb 3-level baroclinic height forecast. The 1000-mb heights are converted to sea level pressures by the same technique as that used with the 6-layer model. C. DEPICTION The computer program determines the positions of sea level isobars and thickness isopleths as sets of x-, y-coordinates by quadratic interpola- tion from the grid point values. The Curve Follower traces out both sets of lines from these coordinates. Isobars are drawn as solid lines at 8-mb intervals with intermediate isobars occasionally drawn as long-dashed lines at 4-mb intervals in areas of weak pressure gradient. (Solid lines at 4-mb intervals are drawn routinely June 15 - October 1.) Isobars are hand labeled by 2-digit numbers, tens and units of pressure in millibars. Positions of low and high centers are plotted by the Curve Follower in the standard way: position of centers These may be labeled occasionally by 3-digit numbers, in millibars with thousands digit omitted. Thickness isopleths are drawn as short dashed lines at 60- meter inter- vals, hand labeled in decameters. Centers of warm and cold pools may be indicated by + labeled in decameters. WBFH NO. I ISSUANCE 5-5 67-1 70-1-67 , the range 15-24%; 30%, the range 25-34%; and so on. The isopleths are drawn at the lower limit of the probability range— the 10% isopleth at the 5% value, the 20% isopleth at the 15% value, the 30% isopleth at the 25% value, etc. Therefore, all points between isopleths and along the lower- valued isopleth have values in the range represented by the assigned per- centage of the lower probability isopleth. For instance, every point along the 30% isopleth and between the 30% and 40% isopleths has a value in the range 25-34%, and, after rounding off to the nearest 10%, is assigned a value of 30%.) WRFH NO. 1 ISSUANCE 5-25 67 .j io-J-67 t » SP-6; QUANTITATIVE PRECIPITATION FORECASTS (QPF) Issued on facsimile on a 1:25 million base chart for the United States and that portion of Canada south of 49° N and west of the northern tip of Maine, 4 times daily in various formats and durations for facsimile transmission plus once daily for teletype transmission. Description 1. FACSIMILE TRANSMISSION: a. A preliminary (late night EST) forecast for the 24 hour period ending at 1200Z the next day. The 24, 36, and 48 hour surface prognoses (see chart SP-3) are the basis for this forecast. b. A primary (early morning EST) forecast for the 12 hour period ending at 0000Z in the evening, the 24 hour period ending at 1200Z the next morning, and an outlook for the 24 hours ending two mornings hence. Here, the 30 hour surface prognosis (see chart SP-2) is used to update the previous forecast. At this time, coded groups and a QPF discussion are also sent out on Service C, under the heading FXUS WBC. c. A mid-afternoon (EST) forecast for the 12 hour period ending at 1200Z the next morning, and for the 24 hour period ending at 1200Z the second morning. The 24, 36, and 48 hour surface prognoses (see chart SP-3) are the bases for these forecasts. At this time, coded groups and a QPF discussion are sent on Service C, under the heading FXUS WBC. d. An evening (EST) check forecast for the 12 hour period ending at 1200Z, the next morning, giving only significant areas of one inch or more. Here, the 30 hour surface prognosis (see chart SP-2) is used to update the previous forecast. 2. TELETYPE TRANSMISSION: a. A mid-day forecast for the 18 hour period ending at 1200Z the next morning. Here, the low-level depiction prognoses (see chart SP-4) are used as a basis for the forecast. This fore- cast is sent as coded groups with a QPF discussion on Ser- vice C lines. b. Special QPF, between scheduled forecasts, are issued, when necessary, on the RAWARC circuit as coded groups with a discussion. WBF.H NO. 1 ISSUANCE 5_27 67 "' 10-1-67 Forecast Procedures 1. NUMERICAL GUIDANCE AVAILABLE: a. The PEP Model (UP-3) numerical cloud, weather and quantitative precipitation forecasts for 12, 24, 36, and 48 hours, which are available prior to the preliminary and mid-afternoon forecasts. b. The 6-Layer Model numerical surface and 1000-500 mb thickness forecasts for 24, 36, and 48 hours, which are available prior to preliminary and mid-afternoon forecasts. Reed 1000 mb and thickness forecasts (3) are available from the barotropic run for the other QPF' s , and as backup for the 6-Layer Model. c. Baroclinic numerical prognoses of 500 mb height and vorticity for 12, 24, and 36 hours, and height only for 48 hours and barotropic height only for 72 hours, which are available prior to preliminary and mid-afternoon forecasts. d. Numerical prognoses of 700 mb vertical motion for 6, 12, 24, and 36 hours, which are available prior to preliminary and mid-afternoon forecasts. 2. OTHER TOOLS AVAILABLE: a. Essentially, the forecast product results from an evaluation of expected distributions of vertical motion and moisture fields, and their interactions. Net vertical motion is thought of in terms of equivalent barotropic, baroclinic, non-adiabatic and frictional contributions. Special attention is given to large- scale terrain influences. The evaluation of initial conditions depends greatly upon observed conditions, as shown by the sur- face map; 6 hourly rainfall and snowfall reports; and upper air circulation, moisture and thermal analyses. The basic tool is the surface prognosis. This maintains internal consistency of all Analysis and Forecast Division (A&FD) weather products. b. 1000-500 mb thickness prognosis which contains modifications is superimposed on 1000 mb height prognosis, with special at- tention to warm advection areas (4), which are available prior to preliminary, primary, mid-afternoon and the evening check forecasts. 3. PREPARATION: The general philosophy of preparation is to interpret observational, numerical, and other objective and semi-objective aids in terms of precipitation location and amount (see also appendix 20). In es- sence, these interpretations depend upon personal experience and aptitude, and the experience of others passed along by written and verbal communication. Continuous endeavor is made to maintain con- tinuity with previous QPF issuances. A principal aim is to fore- WBFH NO. J ISSUANCE 67-1 10-1-67 5-28 f east realistic precipitation patterns. Preparation of Actual Fax Chart Reduction from the working charts (1:20,000,000) to fax transmis- sion scale and tracing for fax transmission requires about 30 minutes. Therefore, charts and data received up to approximately 30 minutes before scheduled fax transmission time may be considered, but full consideration and complete incorporation into the fore- casts requires a lead-time of at least 60 minutes. Depict ion On Fax Chart: The product is depicted as forecast isohyets of precipitation in inches and hundredths at set values of 0.25, 0.50, 1.00, 2.00, 3.00, 4.00, 5.00, etc. Alternate forecast isohyets are used when tight gradients may interfere with quality of fax transmission. The one inch isohyet is the smallest forecast value on the evening check forecast. REFERENCES : 1. Younkin, R. J., LaRue, J. A., and Sanders, F. , "The Objective Prediction of Clouds and Precipitation Using Vertically Integrated Moisture and Adiabatic Vertical Motions", Journal of Applied Meteorology. Volume 4, No. 1, February 1965, pp. 3-17. 2. Kulawiec, M. H. , "Local Cloud and Precipitation Fore- cast Method (SLYH)", Technical Note 13 Fcst-2, Notes to Forecasters No. 2, Weather Bureau, September 1965. 3. Reed, R. J., "Experiments in 1000 mb Prognosis", NMC Technical Memorandum No. 26, Weather Bureau, 1963. 4. STAFF, A&FD, "Synoptic Meteorology as Practiced by the National Meteorological Center", The NAWAC Manual, Part II, March 1963, p. 33. WBFH NO. 1 ISSUANCE 5-29 671 io-i-67 f * SP-7; HEAVY SNOW GUIDANCE FORECASTS Issued on a 1:25 million base chart for the United States and that portion of southern Canada south of 49° N and west of the tip of Maine, 4 times daily in various formats and duration for facsimile transmission plus once daily for tele- type transmission, unscheduled special transmission coded for teletypewriter transmission on RAWARC circuit. Description 1. FACSIMILE TRANSMISSION: a. A preliminary (late night EST) forecast for the 12 hour period ending at 0000Z that evening. Here, the 24 hour surface prog- nosis (see chart SP-3) is the basis for the forecast. b. A primary (early morning EST) forecast for the 12 hour period ending at 0000Z that evening. Here, the 30 hour surface prog- nosis (see chart SP-2) is used to update the previous forecast. Comments on heavy snow forecasts are also sent on Service C lines, under the heading FXUS WBC . c. A mid-afternoon (EST) forecast for the 12 hour period ending at 12003 the next morning. The 24 hour surface prognosis (see chart SP-3) is the basis for this forecast. Comments on heavy snow forecast are also sent on Service C, under the heading FXUS, WBC. d. An evening (EST) check forecast for the 12 hour period ending at 1200Z the next morning. Here, the 30 hour surface prognosis (see chart SP-2) is used as a basis for the forecast. 2. TELETYPE TRANSMISSION: a. A mid-day check forecast for the 12 hour period ending, at 0600Z that night. The 12 and 24 hour surface prognoses (see chart SP-4) are the basis for this forecast. The forecast is also sent as coded groups, with a discussion on Service C lines, under the heading FXUS WBC. b. Special heavy snow forecasts (between scheduled forecasts) are issued to update regular guidance during important snowfall situations. These are coded with discussions, and sent on the RAWARC lines. WBFH NO. J ISSUANCE 5-31 67-7 70-1-67 t F o recast Procedures 1. NUMERICAL GUIDANCE AVAILABLE: a. The PEP Model (UP-3) numerical cloud, weather and quantitative precipitation forecasts for 12, 24, 36, and 48 hours, which are available prior to the preliminary and mid-afternoon forecasts. b. The 6-layer 1 (SP-1) numerical surface and 1000-500 mb thickness forecasts for 24, 36, and 48 hours, which are available prior to preliminary and mid-afternoon forecasts. Reed 1000 mb thickness forecasts also are available from the barotropic run for the other QPF's. c. 6-layer 1 numerical prognoses (see UP-2 and UP-8) of 500 mb height and vorticity for 12, 24, and 36 hours, which are avail- able prior to preliminary and mid-afternoon forecasts. d. Numerical prognoses of 700 mb vertical motion, 6, 12, 24, and 36 hours, which are available prior to preliminary and mid- afternoon forecasts. 2. OTHER TOOLS AVAILABLE: a. Essentially, the forecast product results from an evaluation of expected distributions of vertical motion and moisture fields, and their interactions. Net vertical motion is thought of in terms of equivalent barotropic, baroclinic, non-adiabatic and frictional contributions. Special attention is given to large-scale terrain influences. The evaluation of initial con- ditions depends greatly upon observed conditions, as shown by the surface map; 6 hourly rainfall and snowfall reports; and upper air circulation, moisture and thermal analyses. The basic tool is the surface prognosis. This maintains internal consistency of all Analysis and Forecast Division weather products . b. 1000-500 mb thickness prognosis which contains modifications is superimposed on 1000 mb height prognosis, with special at- tention to warm advection areas (4), which are available prior to preliminary, primary, mid-afternoon and evening check forecasts . 3. PREPARATION: In addition to the tools normally used in forecasting quantitative precipitation, (see also appendix 20) other tools are used to limit forecast heavy snow to areas with favorable tropospheric thermal properties (5,6,7,8). Heavy snow is defined (for these forecasts) as snowfall of 4 inches or more in the specified 12 hour periods. Reed ead 3—layer models used as backup. WBFH NO. ) ISSUANCE 67-7 10-7-67 5-32 A principal aim is to forecast realistic heavy snowfall patterns, although intentionally there is some tendency toward overf orecast- ing areal extent as an alerting mechanism to field forecasters. Heavy snow forecasts are not issued for the high Sierras, higher mountain passes and mountain tops, unless they are included as a part of a general snow area for the lower, more inhabited areas. Lake-effects are considered in forecasting heavy snow for the Great Lakes Region, but areas usually are not outlined except when synop- tic conditions combine with lake-effects to increase the likelihood of more general heavy snowfall. The general philosophy of forecast preparation is to interpret ob- servational, numerical, and other objective and semi-objective aids in terms of heavy snow occurrence and location. Preparation of Actual Fax Chart Complete consistency is maintained with the quantitative precipita- tion forecast for the same period. Therefore, final decision as to location and extent of heavy snow is not made until the correspond- ing period QPF is completed. The normal assumption is that approx- imately 0.25 of an inch of precipitation is the minimum amount necessary for heavy snow. The heavy snow forecast is traced for fax transmission about 15 minutes before scheduled transmission. REFERENCES 1. Younkin, R. J., LaRue, J. A., and Sanders, F., "The Objective Prediction of Clouds and Precipitation Using Vertically Integrated Moisture and Adiabatic Vertical Motions", Journal of Applied Meteorology , Volume 4, No. 1, February 1965, pp 3-17. 2. Kulawiec, M. H. , "Local Cloud and Precipitation Forecast Method (SLYH)", Technical Note 13, Fcst-2, Notes to Forecasters No. 2, Weather Bureau, September 1965. 3. Reed, R. J., "Experiments in 1000 mb Prognosis", NMC Technical Memorandum No. 26, Weather Bureau, 1963. 4. STAFF, A&FD, "Synoptic Meteorology as Practiced by the National Meteorological Center", The NAWAC Manual, Part II, March 1963, p. 33. 5. Fawcett, E. B., and Saylor, H. K. , "A Study of the Distribution of Weather Accompanying Colorado Cyclogenesis", Monthly Weather Review , Volume 93, No. 6, June 1965, pp. 359-367. 6. Penn, S., "The Prediction of Snow vs. Rain", Forecasting Guide No. 2, Weather Bureau, November 1957. WBFH NO. ? ISSUANCE 5^,33 67-1 10-1-67 7. Wagner, A. J., "Mean Temperature from 1000-500 mb as a Predictor of Precipitation Type", Bulletin of the American Meteorological Society, Volume 38 , No. 10, December 1957, ^ pp. 584-590. ( 8. Younkin, R. J., "1000-850 mb and 850-700 mb Thickness Precipitation Type Relations" Unpublished Research Report U. S. Weather Bureau, Knoxville, Tennessee, 6 pp., 1957. Available in the Weather Bureau Library. 9. Goree , P. A., and Younkin, R. J., "Synoptic Climatology of Heavy Snowfall Over the Central and Eastern United States", Monthly Weather Review, No. 11, November 1966, pp. 663-668. Depiction The heavy snow isopleth labeled as 4" appears as a solid line on the heavy snow guidance chart and as a dashed line when superimposed on the QPF guidance chart. t WBFH NO. I ISSUANCE 671 10-7-67 5-34 S P - 8 ; 24-HOUR TEMPERATURE PROGNOSIS Issued for temperatures valid during 12 hour periods each terminating 24, 36, 48, and 60 hours in advance and showing significant isotherms (i.e., 10° F interval in winter and 5° F interval in summer) and significant changes (i.e., >10° F in winter and >. 5° F in summer), presented on four 1:25 mil- lion panels, each covering the United States and that portion of southern Canada south of 49° N, and west of the northern tip of Maine, transmitted twice daily. Description These prognoses are cycled twice daily, as part of: 1. Prog Package A - from 0000Z 2. Prog Package B - from 1200Z (early morning, EST) (mid-afternoon, EST) showing: showing: today's maximum, tonight* s minimum, tomorrow' s maximum, and next night* s minimum. tonight's minimum, tomorrow' s maximum, tomorrow night's minimum, and next day's maximum. These prognoses are also sent on the National Facsimile Circuit with the 60 hour prognosis replaced by the evening check heavy rain or snow fore- cast (see charts SP-6 and 7). Forecast Procedures 1. NUMERICAL GUIDANCE AVAILABLE: a. Forecast Model Two sets of statistical regression equations, one for minimum and one for maximum temperatures, have been developed by the Techniques Development Laboratory in the Systems Development Office of the Weather Bureau. These will be referred to here- inafter as Klein II equations. Klein II temperature forecasts and resulting 24 hour changes are made twice daily, on the NMC computer as part of the RADAT forecast (barotropic mesh) run which begins at 0130Z and 1330Z. These equations use forecast 500 mb heights and 1000-500 mb thickness obtained from the barotropic and Reed models (see charts UP-1 and SP-1) progs. The observed maximum and minimum temperatures* used to start the forecasts are obtained by automatic decoding of surface reports on NMC's IBM 360 and processed in the 7094 computer systems. *These are 12 hour observed maximum and minimum temperatures (see chart AC-4). WBFH NO. 7 ISSUANCE 5-35 67-} J0-I-47 b. Data Used for Derivation of Equations : Fifteen years (1948-1963) of maximum and minimum temperatures at 119 United States and Canadian stations (see appendix 21), /' plus 1000-700 mb thicknesses and 700 mb heights, at NWP grid points, were used to derive the basic forecast equations. Five years of data (1955-1960) were then used to develop a relation between 500 mb heights and thicknesses and 700 mb heights and thicknesses. Also, in the derivation of the equa- tions, a 12 hour lag was used for upper-air parameters and either 12 or 24 hour lag for the previous maximum and/or mini- mum temperatures. In an attempt to get more information on seasonal variations into the equations, the following parameters are also made available to be used in deriving the equations: 1) The number of the day of the year (i.e., 1 to 365) 2) The sine function of the day of the year s Considering 3) The cosine function of the day of the year/ the year as 4) Twice the sine function in "2" A having roughly 5) Twice the cosine function in "3 M J 360 degrees (or days) . These functions represent (in increasing "order") Fourier components of the seasonal variation. Experience has indi- cated that much information on seasonal variation is already contained in the variation of the first term of the equations, since equations are derived for six, two-month periods. Of the terms listed above, all seem to account equally well for f most of the seasonal variation or change in slope of the sea- sonal curve. Therefore, only the day-of-the-year term has been included in later versions (after September-October) of the equations. c . Method Used in Derivation of Equations Separate equations for maximum and minimum temperatures are being derived in two-month increments (beginning with September-October) at the 143 stations, shown in appendix 21. The method used is a modification of the step-wise multiple regression technique known as the screening procedure. In this procedure, the two most significant of the set of available parameters (see paragraph 2 above) are first selec- ted. The more significant of these two is then used to derive a one-parameter equation. The other parameter is tossed back into the "hopper" and the next two most significant parameters are selected. The more significant of these two is combined with the original parameter to form a new regression equation, and so on, until less than a 2% increase in reduction of WBFH NO. J ISSUANCE 67-1 10-7-67 5-35 ' variance is explained by the last two parameters selected. At this point, no new parameters are selected and the fore- cast equation is complete. 2. OTHER TOOLS AVAILABLE: The A&FD temperature forecaster has the following tools available to prepare his forecast: a. The complete set of Klein II temperature and temperature-change forecasts out to 60 hours. b. The package of initial, 12, 24, and 36 hour barotropic prog- noses (see UP-1) and Reed prognoses (see SP-1). c. The A&FD 24, 36, and 48 hour surface prognoses, (see chart SP-3) and accompanying 500 mb prognoses (see chart UP-4). d. A file of observed 24 hour maximum and minimum temperatures. e. The latest surface, cloud and weather, and upper-air analyses. 3. PREPARATION: The temperature forecaster' s job is twofold: a. To eliminate systematic errors in the Klein II forecasts. b. To present temperature and temperature change forecasts which are consistent with other prognoses (e.g., surface, cloud, and weather) in Prog Package A and B (see discussion with chart SP-3). The primary effort by the forecaster is directed toward the tem- perature forecast. The 24 temperature changes which are also de- picted on the fax chart are obtained from a smoothed graphical sub- traction of the forecast isotherms. Limited experience, at NMC, with use of Klein II equations, indi- cates their most svstematic error is lack of amplitude in forecasts of temperature change particularly beyond 24 hours. In areas where large changes occur less frequently (i.e., southern and western United States), the Klein II system shows quite a bit of skill. Depiction On Fax Chart 1. Each panel depicts a minimum or maximum temperature valid dur- ing the 12 hour period ending at the time and for the type (maximum or minimum) of temperature shown on the label. These are considered as the 12 hour maximum or minimum, to be consis- WBFH NO. J ISSUANCE 5_37 67-1 '°-'- 67 tent with the observed temperatures (see chart AC-4) which are used in making the Klein II forecast. Each panel also depicts a 24 hour temperature change ending at the time and for the type (maximum or minimum) of temperature shown on the label. In winter, the basic interval of depiction is 10°F, with 5° interval added where necessary to define the pattern. In sum- mer (May through August) the basic interval is 5°F. 32°F is always depicted in lieu of 30°. All basic isotherms are de- picted as solid lines done by hand. Temperature change isopleths are depicted as dashed lines and are superimposed on the fore- cast isotherms. A zero temperature change isopleth is inserted for clarity over the intermountain west. The isopleths are drawn by hand. V/BFH NO. 7 ISSUANCE 67-1 10-1-67 5 ~ 38 SP-9; SEVERE WEATHER OUTLOOK (WWUS-1) MKC For the contiguous United States two panel 1:20 million scale transmitted once daily at 1200Z. Description One panel depicts areas of general thunderstorms and areas of severe thunderstorms for the 24 hour period from issuance time (see appendix 22) Second panel is a prognosis of the axis of the strongest low level wind (low level defined as not above 5000 feet), the maximum wind at upper levels (range 25,000 to 45,000 feet) and the lifted index, a measure of stability similar to the Showalter Index (see appendix 23). This prognosis verifies 12 hours from transmission time (0000Z) . Prognosis based on OO0OZ upper air data and 0600Z surface data, revised and up- dated by 0600Z upper wind data and 0900Z surface data as required. In addition a written Convective Outlook (AC) is also transmitted over Service A at 1140Z. During the period September 1 to January 31, the WWUS-1 is transmitted only when severe thunderstorms are expected. Otherwise, the notation "No Severe Thunderstorms Expected" appears on the 0S45Z transmission of the radar summary chart (ADUS) . Forecast Procedures 1. NUMERICAL GUIDANCE: Extensive use is made of NMC products received on the National and Forecast Center Facsimile Networks. With the large scale flow pattern established, the SELS forecaster reverts to specially analyzed charts to locate and prognosticate embedded small scale systems for periods of 12, 18, and 24 hours. These are hand- processed. 2. TOOLS AVAILABLE: a. Additional prognoses to establish the stability field and its trend are made. This involves a consideration of both the lower and upper level thermal and moisture patterns and their intensities. b. NMC wind progs are adjusted based on 0600Z wind data. These two steps are also hand-processed. REFERENCES: Atlas, David, et al . , "Severe Local Storms", Meteorological Monographs, Volume 5, No. 27, September 1963, pp. 141-155. WBFH NO. 1 ISSUANCE 5-39 67-1 10-1-67 Philosophy of Forecast The Severe Thunderstorm Outlook is a pictorial presentation of the writ- ten Convective Outlook (AC) transmitted over Service A at 1140Z with the addition of a prognosis of selected parameters verifying at 0000Z. The intent of the Severe Thunderstorm Outlook is to alert all interests con- cerned, for planning purposes or otherwise, to the possibility of future severe local storm development. It is also an alert to the general areas where specif ic severe weather watches and/or forecasts might be is- sued later in the day. The NMC Guidance received, the additional hand- processing performed and the thought processes executed by the SELS fore- caster are directed toward the written AC. The pictorial presentation follows quite readily. Depiction A legend appears on each panel explaining the depiction. Additional clarification : 1. Lifted Index lines are drawn for each 2° C below 0° C^starting with 0° C. 2. The tornado area depictor (cross-hatching) appears only when a tornado watch is in effect at transmission time. 3. The word FEW* and abbreviations SCTD and NMRS refer to the corresponding percentages of the area covered by such thunder- storm activity during the whole 24 hour outlook period, or during the time period indicated when applicable, not any one particular time. The abbreviation ISOLD is used to indicate minimal activity. 4. When severe thunderstorms are forecast to develop along an instability line, the appropriate symbol and beginning time are entered. Ending times are inserted when practical. *FEW - up to 15% coverage SCTD - 16 to 45% coverage NMRS - more than 45% coverage WBFH NO. ? ISSUANCE 67-1 10-1-67 5-40 SP-10; SEA SURFACE WAVE PROG Description 12- and 36-hour prognoses twice a day from 0000Z and 1200Z initial data, produced by computer from a model developed at the U. S. Navy Fleet Numerical Weather Facility (FNWF) at Monterey for the Atlantic north of 30° N latitude on a 1:30 million scale. Data Inputs This program utilizes; 1 . History tapes containing the u/v components of surface geostrophic wind from -18 to +48 hours for each synoptic time . 2. A ship's data list containing all collected ship reports sorted by time (last time first order) with all OSV reports held in a special data reserve. 3. A history tape of wind wave height, direction, and period from -84 hours to +48 hours for each synoptic time. Philosophy of Analysis The surface wind directions are corrected for cross contour flow and stability in regard to direction and speed. The duration is deter- mined with directional limits set at - 22°. The maximum duration is limited to 18 hours according to the French school which considers all seas to be fully developed after that time period. The significant wave height and period are then computed, for the analysis and prog- nosis times per synoptic period, from the following formulae: H l/3 = K 1 V 2 D+K V T l/3 = V ( K 3 +K 4 D)+K 5 where V is the corrected wind speed, D is the duration, and K-, through K5 are empirical constants. An additional correction and limitation for fetch length, offshore flow, and points designated in the FNWF land/sea/ice table is made at this time to limit wave height develop- ment . At this point, a difference field between the wind wave analysis and reported ship heights is formed utilizing oldest reports first (within 9 hours) and superimposing, sequentially, ship reports until all on time reports have been considered. In this operation, differences in excess of 22 feet between the FNWF analysis and reported ship observa- 5-41 WBFH NO. J ISSUANCE 67-1 101-67 tions, and ship reports that show a variance greater than 20 feet be- tween' their reported wind wave and swell groups are rejected. Finally, all OSV and other designated ship reports are placed into the difference field to give maximum weight to these quality reports through last pass insertion. This difference field is smoothed and added to the FNWF analysis, 12 hour and 24 hour prognosis wind wave fields (different smoothing factors and smoothing passes are utilized in the 12 and 24 hour prognoses). The swell height, direction and period are determined from the histori- cal wave fields with only waves 24 hours old and heights greater than 6 feet considered for swell generation and decay. Travel distance and spreading are computed, and swell heights and periods are then deter- mined from: o 81 H D ~ H F i T v ( F 2' T D - • T F H_ height at end of decay T period at end of decay Hp initial height T,., period F d travel distance m mean map factor along decay path C2 empirical constant For practical purposes, only the highest swell (with its direction and period) for a particular grid point is retained. The combined wave analysis/prognosis is formed from the wind wave and swell analysis/prognosis utilizing the following formula: CH'~ = (WH 2 + SH 2 ) 1/2 except where WH is greater than 22 feet, CH = (WH) . The direction and period of the highest wind wave or swell is retained as the combined direction and period. WBFH NO. 1 ISSUANCE 67-1 10-1-67 5-42 Depiction and Coding Height contours in feet for the highest one-third of the waves are de- picted by solid lines at 4-foot intervals labeled by hand. Centers of maximum height and areas of minimum height are hand-labeled as max and min respectively. Arrows indicate direction of wave movement. WBFH NO. ? ISSUANCE 5-43 67-1 IO-J-67 UP-1; FOUR- PANEL NWP BAROTROPIC PROGNOSIS Includes an initial analysis with 12-, 24-, and 36-hour prognoses of 500 mb height contours, and isopleths of abso- lute vorticity, issued twice daily from 0000Z and 1200Z UX selected level data collections. Each panel covers the North American area on a 1:30 million scale chart (see appendix 24). The Equivalent Barotropic Model More detailed information on the equivalent barotropic model is avail- able in the following references: REFERENCES: 1. STAFF, A&FD, NAWAC Manual Part II, Chapter I (starting on page 7). 2. Charney, J. G. , "On a Physical Basis for Numerical Prediction of Large-scale Motion in the Atmosphere", Journal of Meteorology, Volume 6 , No. 6, December 1949 pp. 371-385. 3. Roberts, C. F. , "Present and Future Operational Numerical Prediction Models", ESSA Technical Note 16 Fcst-3, October 1965. IMPORTANT FACTS: Definition of the Equivalent Barotropic Atmosphe re In an equivalent barotropic atmosphere, the absolute vorticity is conserved at that level at which the actual wind speed is equal to the pressure-averaged wind speed. A mathematical expression (or a prognostic equation) which expresses the above relation is called a model because it resembles or approximately describes the actual atmosphere. Thus, the local change of vorticity + advective change of vorticity = 0, or K at ox + v ^- = dy is the simplest form of the Barotropic Model. The vertically averaged winds (u and v) apply at about 500 mb (called the level of non-divergence). 6-1 WBFH NO. 1 ISSUANCE 10-7-67 2. Implied Vertical Motions According to the definition of an equivalent barotropic atmosphere : a. The assumed wind profile most often resembles that asso- ciated with the middle-latitude polar jet at about 250 mb, and b. The sign of the large-scale divergence musb change at least once in the vertical between the surface and top of the atmosphere. c. Therefore, with positive vorticity advection (i.e., vorti- city values increasing upstream) ahead of a trough, large- scale convergence occurs below, and divergence above 500 mb, producing upward vertical motion at that pressure surface. The opposite divergence pattern produces downward motion behind a trough. d. Also, in the equivalent barotropic atmosphere, troughs and ridges have no slope in the vertical, since pressure and thermal patterns are in phase. 3. Engineering of the Equivalent Barotropic Model Several years of operational experience, with the barotropic model, have produced the following terms engineered to correct systematic errors in the forecast: a. HeLmholtz term which reduced large height errors resulting from retrogression of the very long atmospheric waves (numbers 1, 2, and 3). b. Mountain correction term which adds vertical motions (divergence) at 500 mb due to flow over the smoothed mountain ranges used in the model. c. Friction correction term which adds vertical motion (diver- gence) at 500 mb, proportional to the average roughness of the terrain over which the air is flowing. Both the mountain and friction correction terms depend on an accurate forecast of the low-level flow (e.g., at 850 mbs). At present, the barotropic forecast is meshed with an 850 to 500 mb thickness forecast designed to produce a low-level wind fore- cast for use in these two terms. For a detailed description of this meshed barotropic, see: WtFH NO. ? ISSUANCE 67-1 10-1-67 6-2 REFERENCES : 1. Gustafson, A. F., "Mesh Model 1964", NMC Office Note No. 24. 2. Roberts, C. F., "Present and Future Operational Numerical Prediction Models", ESSA Technical Note 16 Fcst-3, October 1965. Derivation and Depiction The "Mesh Model" barotropic forecast is run from an automatic data pro- cessing (ADP) and computer analysis of the UXNA 850 mb and 500 mb selected level data, and begins at 1 1/2 hours after observation time. The ADP and analysis procedures are described under chart UA-1. 1. Prognostic Contours The stream function, the basic parameter, is forecast at the NWP network of grid points spaced about 180 nautical miles apart (appendix 11). These are converted to grid point heights by inver- sion of the balance equation. The location of points, 1/8" apart on the map scale, along each standard contour is determined by quad- ratic interpolation from grid point heights. 2. Prognostic Absolute Vorticity The relative vorticity is calculated at each grid point from the Laplacian 1 (V ) of the forecast stream function. The Coriolis Parameter is then added. Next, points along the isopleths of abso- lute vorticity are interpolated for every 1/8" from grid point values and smoothed 2 . Note that vorticity values are not calculated direct- ly from heights, and are smoothed separately from heights. There- fore, calculation of vorticity values from contours will not neces- sarily duplicate values drawn on the chart. Also vorticity values are directly dependent on grid interval used in their computation. 3. Depiction Isopleth location points for both height contours and absolute vor- ticity are traced out by the Curve Follower directly on the section- al facsimile charts. Height contours are drawn as dashed lines at """In finite differences this means: 4 u taking the sum of the values at grid points 1 O C)0 O 3 1> 2, 3, and 4, and subtracting 4 times the value at 0. (1+2+3+4-4(0)). O A grid interval The initial vorticity isopleths are obtained in a similar manner from the initial stream function field derived from the analyzed balanced height field, WBFH NO. 1 ISSUANCE 6-3 67-1 10-1-67 60 meter intervals, hand labeled in decameters. High and low centers are indicated by +, machine labeled in decameters. Absolute vorticity isopleths are drawn as solid lines at intervals ™ of 2 X 10~ 5 sec - - 1 -, hand labeled in tens and units of 10"^ sec -1 . Centers of maximum and minimum absolute vorticity are indicated by +, machine labeled m tens, units and tenths of 10 sec - . WBFH NO. 1 ISSUANCE 67-1 10-1-67 6-4 UP-2; FOUR- PANEL NWP BARO CLINIC P ROGNOSIS Includes an initial analysis with 12-, 24-, and 36-hour prog- noses of 500 mb contours and isopleths of vertical velocity. Issued twice daily based on data available 3+25 hours after 0000Z and 1200Z upper-air observation times. Each panel covers the North American area on a 1:30 million scale (see appendix 24). The 6-L ayer (PE) Numerical Prediction Model The prognostic equations used in the model are the original Newtonian equations of motion which balance accelerations (along any coordinate) with the forces acting in that direction. For instance, when pressure is the vertical coordinate, the first equa- tion of motion becomes: ttt + W.Vu + uu t— (total acceleration in x-direction) = at dp fv (coriolis force in x-direction) - ~— (pressure force in x-direction) + F x (frictional forces in x-direction) . The general equations are capable of forecasting several types of wave motion in a fluid such as the atmosphere (e.g., sound waves, gravity waves, Rossby waves). In the 3-level filtered model, the Newtonian equations are combined to form a prognostic vorticity equation which circumvents some of the mathe- matical and physical problems that seemed insurmountable a few years ago in operational NWP. In both models, motion of sound waves is eliminated by use of the hydrostatic approximation. In the filtered model, gravity waves are eliminated by use of the balanced or non-divergent wind. Gravity waves are allowed to propagate in a controlled manner in the primitive equation model. Therefore, the primitive equation model must be integrated in much shorter time steps than the filtered model (i.e., 10 minutes versus 1 hour). As a result, the present PE model requires about 60 minutes (including initialization) to run out to 36 hours on the CDC 6600, in contrast to about 50 minutes for the 3-level model on on the IBM 7094 II. IMPORTANT FACTS: 1. Basic equations used a. The two horizontal equations of motion, used to forecast u- and v-coraponents of the wind (in the x- and y-directions on the NWP grid of appendix 11). & FF J WBFH NO. J ISSUANCE 6-5 671 IO-J-67 b. The hydrostatic equation and the equation of state which relate pressure, temperature, and height. c. The thermodynamic energy equation used to forecast temperature. d. The equation of mass continuity which relates mass divergence and vertical motion, and is used to forecast vertical pressure change in this model. This system of equations is complete; that is, it allows all depend- ent variables in the system to be forecast. The primary forecast variables are the wind, temperature and pressure. 2. The vertical structure The equations are written in terms of a special vertical coordinate sigma (cr). The sigma system is based on pressures at three materi- al surfaces: the smoothed profile of the earth's surface which ap- proximates the real topography, p*; the tropopause, p**; and a pres- sure level in the lower stratosphere above which the atmosphere is assumed to have no meteorological significance, p . The troposphere is subdivided into a boundary layer and three other layers and the stratosphere into two layers. The value of o at any given pressure level is determined in the boundary layer, the troposphere and the stratosphere from p - p O" = Pi - P u where the subscripts indicate upper and lower. The vertical struc- ture is illustrated schematically in appendix 39. 3. Initialization (15 minutes on CDC 6600) To obtain a set of initial data for the PE model, NMC analyzes data over the Northern Hemisphere as far south as 10-15° north latitude. a. Sea-level pressures and surface temperatures, from which 1000 mb heights are computed. b. Heights and temperatures at nine other constant pressure surfaces, 850, 700, 500, 400, 300, 250, 150, and 100 mb. (Temperatures at 1000 mb are computed.) c. Pressures and temperatures at the tropopause. Pressures and heights for the a- surf aces (including pressures for the earth's surface for which height is given by the smoothed pro- file) are interpolated. Mean potential temperatures are computed from the hydrostatic equation and mean non-divergent wind compo- nents are obtained from a solution of the balance equation for each WBFH NO. 1 ISSUANCE 671 70-1-67 6-6 of the -(vertical velocity) equation from: 1) differences in advection of absolute vorticity at 800 and 500 mb and WBFH NO. ) ISSUANCE 67-1 10-1-67 6-10 2) Laplacian of thickness advection in layer 800 to 500 mb. The computed vertical velocities represent the mean in the layer 800 to 500 mb and apply at the midpoint of the layer, 650 mb. Depiction of Output 1. Contours Initial and 12-, 24-, and 36-hour prognostic heights at 500 mb are determined at the network of NWP grid points spaced about 180 nautical miles apart (appendix 11). The location of points 1/8" apart on the map scale along each standard contour is obtained by quadratic interpolation from the grid point heights. The Curve Follower traces out these location points on a 1:30 million scale hemispheric base chart. These contours are then traced ("wheeled") onto the sectional facsimile base chart by hand as dotted lines at 60 meter intervals. Contours are hand-labeled in decameters. 2. Vertical Velocity Vertical velocities at 700 mb are averaged over twelve consecutive 10-minute time steps — in the 4th and 5th, 10th and 11th, 22nd and 23rd, and 34th and 35th hours of the forecast period. The values of vertical velocity at each grid point, then, are centered at 5, 11, 23, and 35 hours after observation time for the PE Model. Initial 500 mb contours are traced on the 5-hour vertical velocity forecast. The 3-Level Baroclinic Model furnishes grid point values of ver- tical velocity for the initial (actually one hour after observation time) and 12-, 24-, and 36-hour prognostic times. Location points 1/8" apart on the map scale along standard isopleths of vertical velocity are determined by quadratic interpolation from the grid point values. The Curve Follower traces out these loca- tion points to draw the isopleths as solid lines at intervals of one microbar per second. 2 (During the months, April-September the interval is .5 microbars per second.) Isopleths are hand-labeled in microbars per second, which may be converted to centimeters per second by multiplying by 1.12 at 700 mb (PE Model) and by 1.19 at 650 mb (3-level model). Positive values indicate upward motion and negative values downward motion. Centers of maximum upward and The line is produced by a small hand device containing an appropriately notched wheel 3/4" in diameter. 2 1 millibar = 1000 microbars WBFH NO. ? ISSUANCE 6-11 67-1 101-67 downward vertical velocities also are interpolated and printed out by the Curve Follower as + labeled in tenths of microbars. (Comparisons made at NMC have shown that vertical velocities from the 3-level baroclinic model are systematically weaker than those computed manually for the layer 1000-500mb. The normal method uses a moist-adiabatic stability value instead of the climato logical value used in the numerical model which does not include the layer below 800 mb where significant temperature advection occurs.) WBFH NO. J ISSUANCE 6-12 67-J 101-67 UP- 3; MEAN RELATIVE HUMIDITY FORECASTS prepared twice a day from 0000Z and 1200Z data covering the North American area on a 1:30 million scale. Chart consists of four panels including an initial analysis and 12-, 18-, and 24-hour forecasts of the mean relative humidity in layer from surface to near 400 mb. Initial Analysis The initial moisture analysis procedure is as follows: a. The initialization procedure for the PE model provides mean potential temperatures in each a-layer and pressures on each cr-surface (appendix 39) at each NWP grid point (appendix 11). Prior to the moisture analysis, saturated total precipitable water amounts, W are computed for the lowest three layers of the model from these parameters. b. All available radiosonde observations are employed for the com- putation of observed precipitable water surface to 400 mb from the temperature-dewpoint/pressnre observations at the sounding sites. This process is described under chart AC-3. c. All SM coded synoptic surface observation locations in blocks 70-79 (North America and environs) reporting precipitation at or near the station, at observation time or in the past hour, are assigned a mean relative humidity equal to the saturation value. The saturation value has been set at 80% (except 70% May through September) because of observational evidence that precipitation can occur even when parts of the air column are unsaturated. Present weather (ww) code 15, 16, 18, 21-23, 25-27, 29, 58-75, and 79-99 are considered as indicators of precipitation. Saturated precipitable water totals at the observation sites, W g , are determined by bilinear interpolation from the previous- ly computed grid point values. Multiplication by the appro- priate saturation mean relative humidity for the season gives the reduced saturated precipitable value for the observation site: W s = .8W S The computed precipitable water from the ww group takes pre- cedence over that computed from the radiosonde. d. Values of "observed" total precipitable water, W, at each grid point are determined from the radiosonde and SM observation point values by the NWP analysis procedure (see chart UA-1). WBFH NO. 7 ISSUANCE 6-13 671 10-1-67 e. The "observed" precipitable water at each grid point is con- verted to mean relative humidity by dividing by the reduced A saturated precipitation total W , for 80% (or 70%) saturation relative humidity and multiplying by 100: R.H. = 100 JL A W s This procedure allows the relative humidities to have the full normal range of - 100% 1 . Numerical Model The mean relative humidity forecasts are produced by the primitive equation precipitation (PEP) model which is a part of the 6-layer (PE) numerical prediction model (see charts UP-2 and UP-4). Forecasts are made for the lowest three layers of the PE model (appendix 39): the boundary layer and the lower two layers of the troposphere (top about 420 mb). FORECAST EQUATION The basic forecast equation for precipitable water is derived from: 1. The moisture continuity equation which, in the a-system, becomes: |3 = - WVq - a IS dt Scj = - WVq - ^hl - q |2 da da where a = —, the a-system vertical velocity equivalent. dt This equation states that, when moisture is conserved, the local change of specific humidity q is given by the horizontal and vertical advections of specific humidity. x To reconcile values of initial relative humidity with those on National Facsimile 18 and 81, chart AC-3, multiply PEP relative humidities by 0.< (except 0.7 May through September). WBFH NO. 1 ISSUANCE 67-1 10-1-67 6-14 2. The equation for precipitable water in the a-system for a layer with upper boundary u and lower boundary 1: P °1 W = 12 ( qSa u u where p is the difference in pressure between a-surfaces r a and g is gravity. The basic forecast equation for precipitable water is developed by differentiating the W equation with respect to time and com- bining with the moisture continuity equation: BW P a r. CT 1 ... „ . Pa r CT 1 9a . _ = J \V.Vqoa +F J q^oa °u a u P a P a l o(aq) , W B Pa ' ~ ~d^~ 9ct + p^ ~ CT u The major contribution to change in W comes from the first two terms on the right hand side: 1. The integral of the quasi-horizontal advection of spe- cific humidity by the wind in the layers. 2. The integral of moisture divergence resulting from stretching and shrinking of vertical columns in the model . The third term is the vertical flux which is assumed to be zero in the model — no inflow at the bottom and no outflow at the top. The last term gives the time-rate-of-change of pressure difference between the a-surfaces. PARAMETERIZATION The initial moisture analysis and each forecast time step in the PEP model provides W, the total precipitable water in the layer WBFH NO. 1 ISSUANCE 6_15 67-1 10-1-67 surface to 400 mb, at each NWP grid point. An idealized vertical distribution of specific humidity is assumed: oW where ex, a function of pressure, is a modeling parameter which is approximated from climatological radiosonde data as in the earlier SLYH model [l]. With this expression and the appropriate value of a, specific humidities in each of the three a-layers, the boun- dary layer and the lower two tropospheric layers, may be determined from W, the total precipitable water in the three layers. From the values of q in each layer, the precipitable water in each layer is computed by the equation for precipitable water so that: REFERENCE w = w B ♦ Wi * ^w T/2 1. Younkin, R. J., J. A. LaRue , and F. Sanders, 1965: ' The Objective Prediction of Clouds and Precipitation Using Vertically Integrated Moisture and Adiabatic Vertical Mot ions, y Journal of Applied Meteorology, 4, 3-17. FORECAST PROCEDURE The finite difference form of the precipitable water tendency equation is integrated in 10-minute steps along with the PE model. The PE model provides values of mean u- and v-components of the wind in each layer at each grid point and pressure differences between a-surfaces for the specific humidity advection term and the last term in the forecast equation. Similarly, values of a on each a-surface are provided for the moisture divergence term. The required integrations are carried out with the given values of a at the a-surfaces. Tendencies of W are determined for each 10-minute time step at each NWP grid point and added to the value of W to give a new value for the next time step in each of the three a-layers. The three W values are summed to give a total value of W for the three layers. At the completion of each time step, the forecast W for the three layers is compared with W s , 80% (70% May through September) of the saturated precipitable water W determined by the prognostic mean potential temperatures from the PE model in the layers involved. Any excess precipitable water is removed and accumulated for pre- cipitation output. The remaining total precipitable water W is parameterized for q and W in each of the three a-layers. The fore- cast procedure is repeated with the simultaneous forecast values WBFH NO. J ISSUANCE 67-1 J0-7-67 6-16 of mean u- and v-components and potential temperatures in the three layers and pressure and - and v-components of the wind are inter- polated to the constant pressure surfaces from the grid point values in the cr-layers above and below assuming linear variation with a function of pressure rr 1 . 1 tt is the ratio of absolute temperature to potential temperature, 1000/ WBFH NO. ] ISSUANCE 6-23 67-? 10-J-67 Heights on the constant pressure surfaces are computed by means of the hydrostatic equation from interpolated potential temperatures and heights and pressures on the closest c-surface above or below the level in question. 2. 3-Level Model The 3-level baroclinic model used as back-up forecasts stream functions at grid points on the 800 mb, 500 mb, and 200 mb surfaces, The stream function field is converted to grid point heights on these surfaces by inversion of the balance equation 1 . 700 mb and 300 mb heights are interpolated using an equation of the type H = A + B.H g50 + C-H 500 + D.H 200 The constants applying at all latitudes have been determined for each season from a year of radiosonde data. Temperatures at grid points on the constant pressure surfaces are derived from the forecast heights using regression equations of the same type as those used for interpolating 700 mb and 300 mb heights. Wind velocities at grid points are computed from the forecast height field on the constant pressure surfaces using the geo~ strophic wind equation. Pep i c t ion A special computer program locates points 1/8" apart on the map scale along standard isopleths of height, temperature and wind velocity on e each of the constant pressure surfaces by quadratic interpolation from the grid point values. The Curve Follower then traces out these loca- tion points to draw the various isopleths on preprinted facsimile base maps (except isotherms). 1. Contours Height contours are drawn as solid lines at 60 meter intervals on 700 mb and 500 mb charts. On 300 mb and 200 mb charts, contours are drawn as solid lines at 120 meter intervals, with intermediate contours as long-dashed lines at 60 meter intervals in areas of weak gradient. Contours are hand-labeled in geopotential decameters, (thousands digit is omitted at 200 mb). Low and high centers are •'■The balance equation usually is used to determine the stream function field, from which balanced (non-divergent) winds may be computed, when the height field is known. WBFH NO. 1 ISSUANCE 67-1 70-1-67 6-24 indicated by "L" and "H" symbols which have the relation shown here to the prognostic center. Lh * — — position of center ' \ \ 2. Isotherms Isotherms are drawn by the Curve Follower on a hemispheric base chart and are then "wheeled" 1 on the facsimile charts at 5°C inter- vals as dotted lines labeled by hand stamps with appropriate tem- peratures circled. 3. Isotachs Isotachs are drawn as dashed lines at 20 knot intervals, hand- labeled oy appropriate velocity with K appended. 1 The line is produced by a small hand device containing an appropriately notched wheel 3/4" in diameter. WBFH NO. 1 ISSUANCE 6-25 67-? 101-67 U P - 6 ; 36-H OUR 500 MB 6- L AYER HEIGHT ERROR Issued twice daily from 0000Z and 1200Z upper air observa- tions for the front half of the Northern Hemisphere on a 1:30 million scale chart (appendix 14). N umerical Mo dels 36-hour 500 mb prognostic heights are produced by the 6-layer (PE) numerical prediction model 1 described under charts UP-2 and UP-4 for the hemispheric network of NWP grid points (appendix 11). The verifying 500 mb heights come from the computer automatic data processing and analysis procedures which begin 3+25 hours after observation time. 95% of the data has been received by this time through operational and special communication channels. Procedures are similar to those described under chart UA-2. Derivation and Dep i c t i o n Analyzed 500 mb heights are subtracted from 36-hour prognostic 500 mb heights to give an algebraic forecast height difference for each grid point. A special computer program determines the location of a set of points 1/8" apart on the map scale along standard isopleths of height error by quadratic interpolation from the grid point values. The Curve Follower then traces out these location points to draw the isopleths as solid lines on a preprinted facsimile base map. The zero line and lines of positive and negative 60 meter increments are drawn. Isopleths of error are hand-labeled in decameters. Positions of maximum height error are printed by the Curve Follower as + or - as appropriate, labeled in decameters. 1 3-level baroclinic model used as back-up. WBFH NO. 1 ISSUANCE 6-27 67 _j JO-1-67 M P - 7 * NWP LIFTED INDEX PROGNOSES Prepared twice a day from 0000Z and 1200Z upper air data covering the North American area on a 1:30 million scale. Chart consists of four panels including an initial analysis and 12-, 24- and 36-hour prognoses of the Lifted Index. Description 1. Definition The lifted index is defined as the 500 mb temperature minus the temperature of a parcel lifted from near the surface of the earth to 500 mb. Negative values indicate instability. 2. Numerical Model The lifted index initial analysis and prognoses are produced by the 6-layer CPE) numerical prediction model described under charts UP-2 and UP-4. In the model, the analyzed or forecast mean pres- sure, temperature and dewpoint in the boundary layer (appendix 39) are taken to be those describing a parcel which then is raised to 500 mb. The resulting parcel temperature is compared with the analyzed or forecast 500 mb temperature. The difference gives the analyzed or forecast lifted index. The parameters are derived from the model as follows: a. Pressure The boundary layer in the model is fixed at 50 mb above the surface of the earth. The pressure at the surface of a highly smoothed topography representing the real terrain is computed in the initial analysis procedure and forecast for each 10-minute time step (described under chart UP-2). The mean pressure representing the pressure of the layer is given in millibars by: p = p* _ 25 (where p* is the pressure at the surface). b. Dewpoint The Primitive Equation Precipitation (PEP) model (de- scribed under chart UP- 3 ) forecasts the total precipi- table water W in a layer which includes the lowest three a-layers of the PE model (appendix 39), from the surface to near 400 mb. An assumption about the vertical distri- bution of moisture must be made in order to determine the portion of the total precipitable water to be allotted WBFH NO. 7 ISSUANCE 6-29 67-J 70-J-67 to the boundary layer. A modeling parameter 125 knots at 300 mb) looking downstream between the trough and upstream ridge where the averaged vertical scala r shear (as given on chart UP-10) is greater than 6 knots/1000 feet. This area is most likely to have moderate or great- er CAT when, on the latest 300 mb chart, an area of cold air advection is also indicated as impinging on the left side of the jet stream. (b) In the "entrance zone" between two confluent jet cores in the region where the cores are 3 to 5 degrees, or less, of latitude apart. (c) In sharp, V-shaped troughs which slope rapidly with elevation below 300 mb. (d) In the "neck" of cut-off lows. (e) To the right (looking downstream) of strong anti-cyclon- ic ally curved jet streams. (f) Over mountain ranges, when the jet core crosses at right angles to the major axis of the range, and winds at the top of the mountain are at least 25 knots. The vertical extent of CAT area is generally forecast no higher than 2000 feet above the tropopause and within the layers in which the conditions listed above are occurring. Often, however, tools are not available to define the ver- tical extent of CAT 15 to 18 hours in advance. Recent references containing material used in NMC* s CAT forecasts are: REFERENCES : 1. Kadlec, P. W". , "A Study of Flight Conditions Associated with Jet Stream Cirrus, Atmospheric Temperature Change, and Wind Shear Turbulence", Final Report USWB Contract CWB-10888, June 1965. 2. Reiter, E., and Nania, A., "Jet Stream Structure and CAT", Journal of Applied Meteorology , Volume 3, No. 3, June 1964. 3. Sorenson, J. E., "Synoptic Patterns for CAT", United Air Lines Meteorology Circular, No. 56, December 21, 1964, 4. George, J. J., "Airline Practices in Forecasting Clear Air Turbulence", Proc . ION-SAE Conf . . CAT Meeting, Washington, D. C, February 23-24, 1966. WBFH NO. J ISSUANCE 67-J 70-J-67 6 ~ 46 5. Hanson, D. M. , et al., "Procedures for Forecasting Clear Air Turbulence", OFDEV Technical Note No. 5, USWB, January 1962. 6. Colson, De Ver, "Analysis of Clear Air Turbulence Data for March, 1962", Monthly Weather Review, Volume 91 , No. 2, February 1963, pp 73-82. 7. Harrison, H. T., and Sowa, D. F., "Mountain Wave Exposure on Jet Routes of NWAL and UAL", United Air Lines, Meteorology Circular No. 60, February 1, 1966. WBFH NO. J ISSUANCE 6-47 67 ., 10-1-67 UP-12; ANC HIGH ALTITUDE FORECASTS Significant weather prognosis 700-150 mb from Anchorage High Altitude Forecast Office covering routes from the pacific Northwest and Alaska to Japan (PN-1 cut, appendix 25) on a 1:20 million scale. Transmitted four times daily, valid at 0000Z, 0600Z, 1200Z, and 1800Z. The corresponding 700 mb, 500 mb, 300 mb, and tropopause/vertical wind-shear prog- noses of the High Altitude package are computer produced at the National Meteorological Center and are described under chart UP-9. Amendments AIREPS within +3 hours of valid time are plotted on the appropriate 300 mb prog prepared by NMC. Areas with serious wind and/or temperature errors (040° and 40 knots for winds and 5° for temperatures) are amended by issuance of a plain language message to facilities at Anchorage, Cold Bay, Kodiak Naval Base, Vancouver, Seattle, San Francisco, and Tokyo. These amendments normally apply corrections to prog charts by zones within specified latitudes, as, for example, REF ANC 300 MB PROG VALID 26/1 200Z INCR WNDS BY 60 TO 80 KT ZONES 34, 35, 36, 01 FROM 45 TO 52N. ON 26/1800Z PROG INCR WNDS ZONES 33, 34, 35 BY 40 TO 60 KT FROM 46 TO 51N. If the error persists for more than two successive progs, the situation is brought to the attention of the Chief Meteorologist at NMC via the High Altitude Intercom. Significant Weather 1 . GUIDANCE a. Objective 24- and 30-hour surface prognoses from the 6-layer (PE) numerical prediction model (chart SP-lA) for valid fore- cast times. b. Operational numerical 700 mb, 500 mb, 300 mb and tropopause/ vertical wind-shear prognoses (charts UP-9 and UP-10A) for valid forecast times. c. 24-hour numerical vorticity and vertical motion prognoses (chart UP-8A) from 0000Z and 1200Z initial data. 2. TOOLS AVAILABLE a. Preliminary manual surface analyses for the North Pacific from the National Meteorological Center (chart SA-2) available for 0000Z, 0600Z, 1200Z, and 1800Z. b. 500 mb computer analyses for the North Pacific available for 0000Z and 1200Z (chart UA-3). WBFH NO. I ISSUANCE 6-49 67 .j 10-1-67 c. 300 mb computer analyses for the northern portion of the North Pacific available for 0000Z and 1200Z (chart UA-3A). d. Locally prepared 1:7.5 million surface analyses (Northeastern Pacific). e. APT cloud mosaics (North Pacific east of 165° east longitude) f. Nephanalyses g. AIREPS h. Norwegian models 3. PREPARATION: Analyzed surface frontal positions and isobars on the NMC 1:20 mil- lion preliminary surface analyses for the North Pacific are modi- fied as necessary to fit late ship reports and delayed Russian data. The NMC guidance surface progs are used as a first approxi- mation for prognostic fronts and isobars, but modified to accommo- date latest surface developments. Prog is completed at H + 10 enabling the forecaster to utilized the synoptic surface map 18 hours prior to valid time. Cloud structures are based on the usually accepted models, heavily-weighted toward the latest APT pictures. Areas of suspected turbulence (other than frontal or thunderstorm) are based largely on horizontal and vertical wind shears associated with a jet stream, zones of sharp contour curva- ture at 500 and 300 mb, vicinity of the jet over rapidly deepening storms, on the right side of the jet stream in zones of anticyclon- ic curvature, and over mountainous terrain under strong trans-moun- tain flow conditions. APT cloud photographs showing well-developed transverse waves (normal to jet stream flow) also serve as guidance for turbulent areas. Locations of the 0° isotherm at 5,000 and 10,000 feet (rarely at 15,000 feet) are based on the isotherms on the concurrent 700 mb prog prepared by NMC for the ANC High Altitude Area. Depiction 1. Prognostic surface fronts are depicted by heavy solid lines; isobars by thin solid lines labeled in millibars. Pressure centers are in- dicated by high and low symbols labeled in millibars. 2. Locations of 0° C isotherm at 5,000, 10,000, and 15,000 feet are in- dicated by short-dashed lines appropriately labeled. 3. Cloud areas are enclosed by scalloped lines and labeled with eights of coverage and type. WBFH NO. 1 ISSUANCE 67-1 10-1-67 6-50 4. Turbulence areas are enclosed by heavy long-dashed lines and labeled by symbols (—A- moderate and_/\_ severe) . "Spot" symbols are used also. 5. Icing is indicated by appropriate symbols (^moderate and kiitf severe). 6. Thunderstorms are indicated by symbol |4 . 7. Vertical extent of significant weather is indicated by bases and tops in hundreds of feet. , (.- vVBFH NO. 1 ISSUANCE °" ■"■ 67-1 I0-I-67 Up_i3- SFO HIGH ALTITUDE FORECASTS 18-hour prognoses of 700 mb, 500 mb, 300 mb, composite 200 mb/tropopause and composite surface/significant weather (surface to 150 mb) from San Francisco High Altitude Fore- cast Office on a 1:20 million scale covering routes from Pacific Coast to Hawaii (cut PA-3, appendix 25). Valid about 12 hours after transmission time at 0000Z, 0600Z, 1200Z, and 1800Z. Forecast procedures 1. GUIDANCE: NMC charts are relied upon for basic guidance, refined with respect to local detail and up-dated as necessary in view of later data received, especially from aircraft in flight. 2. TIME AVAILABLE: a. Approximately one and one-half hours average time is required for development of each prognostic chart and for copying in "finished" form for Fax transmissions. b. Data cut-off time is H plus 6 hours for basic observations (surface, RAOB, and RAWTN) and H plus 8 hours for reports from aircraft in flight. 3. PREPARATION: The sea-level, 700 mb, 500 mb, and 300 mb levels are inter-related hydrostatically ; from 300 to 200 mb, a vertical relationship of troughs and ridges is primarily assumed but modified as necessary to accommodate observed slopes and/or differences in amplitude and strength of gradient. Clear Air Turbulence is forecast on the basis of vertical wind shears and strong horizontal wind shears such as at sharp troughs or shear lines. Tropopause heights and configurations are geared to 500 mb isotherms as revealed at observed points, and thus are in a general sense related to potential temperatures. REFERENCES : 1. Stanford Research Institute publication of June 1964 "Clear-Air Turbulence and Its Analysis", under Weather Bureau contract CWB-10624. „ WBFH NO. 1 ISSUANCE 6-53 67-1 '0-1-67 2. Stanford Research Institute publication of May 1963, "Detailed Structure of the Atmosphere in Regions of Clear-Air Turbulence", contract CWB-10324. 3. Eastern Airlines "Study of Flight Conditions. .and Wind Shear Turbulence", June 1964, under Weather Bureau contract CWB-10674. 4. Eastern Airlines "Flight Data Analysis. .. .of Clear-Air Turbulence", June 1965, CWB-10888. 5. United Airlines Meteorological Circular #56, December 1964, "Synoptic Patterns for Clear-Air Turbulence". Depiction 1. Height contours are drawn as solid lines. Intervals are 200 feet at 700 mb and 500 mb with intermediate long-dashed contours at 100 feet in areas of weak gradient. At 300 mb and 200 mb, intervals are 400 feet with intermediate long-dashed contours with arrowheads in direction of flow at 200 feet. Contours are labeled in feet. Height centers are indicated by high and low symbols. 2. Isotachs are drawn as short-dashed lines at 20 knot intervals up to 140 knots and 40 knot intervals above 140 knots labeled in knots by stamps. The 10 knot isotach is indicated also. "Spot" winds are indicated by arrows and barbs: at 600 mb on the 700 mb chart, at 400 mb on the 500 mb chart, and at 250 mb on the 300 mb chart. 3. Encircled "spot" temperatures are plotted in sufficient density to delineate the thermal field. 4. Heavy long-dashed lines indicate the intersection of the tropopause with constant pressure surfaces at intervals of 50 mb at and below 150 mb appropriately labeled on the composite 200 mb/tropopause chart. Mean tropopause temperatures are entered in boxes along these lines. 5. Composite surface/significant weather prognosis. a. Fronts are depicted in the usual manner (appendix 2). Isobars are depicted by solid lines labeled in millibars. Pressure centers are indicated by high and low symbols. b. Locations of the 0° C isotherm at 2,500 foot intervals of height are indicated by short-dashed lines appropriately labeled. WBFH NO. 1 ISSUANCE 6-54 671 101-67 c. Cloud areas are enclosed by scalloped lines and labeled by eighths of coverage and type. d. Turbulence areas are enclosed by heavy broken lines and labeled by symbols ( _A_ moderate and _^_ severe). "Spot" symbols are used also. e. Icing is indicated by appropriate symbols ( Mf moderate and Vjjp severe). f. Thunderstorms are indicated by symbol Ki . g. Vertical extent of significant weather is indicated by bases and tops in hundreds of feet. WBFH NO. J ISSUANCE 6-55 67-1 10-7-67 yp„14; JFK HIGH ALTITUDE FORECASTS Significant weather prognosis 700-150 mb from Kennedy High Altitude Forecast Center covering the northern portion of the North Atlantic (NT-/ cut, appendix 25) on a 1:20 million scale. Transmitted four times daily, valid at 0000Z, 0600Z, 1200Z, and 1800Z. The corresponding 700 mb , 500 mb, 300 mb, and tropopause/vertical wind shear prognoses of the High Altitude package are computer produced at the National Meteorological Center and are described under chart UP-9. Amendments JFK is responsible for monitoring and amending the numerically produced operational prognostic package for the North Atlantic transmitted on the High Altitude Facsimile Circuit. Amendments are issued in narrative form via local teletype, telautograph and facsimile in the New York City area and encoded in digital format for possible future relay by NMC over the high speed AIRINC teletype circuit. Significant Weather 1 . GUIDANCE a. Objective 24- and 30-hour surface prognoses from the 6-layer (PE) numerical prediction model (chart SP-1A) for valid fore- cast times. b. Operational numerical 700 mb, 500 mb, 300 mb and tropopause/ vertical wind shear prognoses (charts UP-9 and UP-10A) for valid forecast times. 2. TOOLS AVAILABLE a. Preliminary manual surface analysis for the North Atlantic from the National Meteorological Center (chart SA-2) available for 0000Z, 0600Z, 1200Z, and 1800Z updated at JFK with late and supplementary data. b. 500 mb and 300 mb computer analyses for the North Atlantic available for OO00Z and 1200Z (chart UA-3) updated at JFK with late and supplementary data. c. Observed and forecast vorticity fields (charts UA-2 and UP-8). d. Aircraft reports from the North Atlantic. e. Satellite pictures (APT) WBFH NO. 1 ISSUANCE 6-57 67 _, jo-l-47 D e p i ction 1. Prognostic fronts are depicted by solid lines pipped in the usual manner. Pressure centers are indicated by high and low symbols labeled in millibars. 2. Location of the 0° C isotherm at 10,000 feet is indicated by a short-dashed line appropriately labeled. 3. Cloud areas are enclosed by scalloped lines and labeled with eights of coverage and type. 4. Turbulence areas are enclosed -by heavy long-dashed lines and labeled by symbols (—A— moderate and _^\L severe) . "Spot" symbols are used also. 5. Icing is indicated by appropriate symbols ( ViL> moderate and Ulf severe) . 6. Thunderstorms are indicated by symbol |"£ . 7. Vertical extent of significant weather is indicated by bases and tops in hundreds of feet. WBFH NO. J ISSUANCE , co 67-7 101-67 UP-15; MIA HIGH ALTITUDE FORECASTS Composite surface/significant weather (500-150 mb), 500 mb, 300 mb, and composite 200 mb/tropopause prognoses from the Regional Center for Tropical Meteorology (RCTM) on a 1:20 million scale Mercator projection true at 22.5°N latitude, valid at 0000Z, 0600Z, 1200Z, and 1800Z, about ten to twelve hours after transmission time. Area covered is equator to 46°N latitude between 120°W and 50°W longitude with an inset in lower left corner cover- ing equator to 12°S latitude between 88-80°W and 73°W longitude. For the 0600Z valid time an additional area from the central Atlantic to the African coast is attached to complete a forecast route from New York to Dakar. (See cut CA-/, appendix 16.) Significant weather, 300 mb, and 200 mb prognoses valid at 0600Z for area equator to 43°N latitude between 70°W and 5°E longitude are trans- mitted directly to San Juan. Forecast Procedure 1 . GUIDANCE : The 24- and 30-hour NMC operational and guidance High Altitude numerical prognoses (see charts UP-5, UP-9, and UP-10A) are used as guidance for the portion of the Miami High Altitude prognoses north of 30°N latitude. By agreement, the 24-hour 500 mb, 300 mb, and tropopause prognoses and the 30-hour 200 mb prognosis verify- ing at 0000Z and 1200Z are copied over the United States. South of 30°N latitude, the prognoses are based on the RCTM analyses and the approach to the forecast problem is subjective. 2. TIME AVAILABLE: The numerical prognoses used as guidance are available on the High Altitude Facsimile Circuit two to three hours before transmission time for the MIA prognoses valid at 0000Z and 1200Z and about five hours before those valid at 0600Z and 1800Z. Upper air data from the Carribean and the tropical Atlantic are not received on a strict schedule. Data received up to two and one- half hours before transmission time are considered. In data-sparse areas, later data may be considered if time permits. A minimum of one and one-half hours is needed for completing the 500 mb, 300 mb, and 200 mb prognoses and checking for consistency. About one hour is necessary for preparing the prognoses for fac- simile transmission. About forty-five minutes is required for preparation of the surface/significant weather prognosis. WBFH NO. 1 ISSUANCE 6-59 67 ., 10-1-67 3. PREPARATION: The following procedure is used in preparation of the forecast: a. Identifying the basic features in and near the forecast area. b. Determining the past history of these features by inspec- tion of preceding analyses. c. Drawing a preliminary prognostic chart (subjective). d. Comparing with the NMC numerical guidance for the valid time and making minor adjustments to mesh the Miami low latitude forecast with the NMC numerical mid-latitude forecast. Cases involving substantial disagreement are resolved if time permits. Aviation and area forecasters may be consulted locally and/or NMC by telephone. There is no provision for transmission of late charts. Conse- quently, time for consultation must be limited to permit completion of the prognostic charts by the assigned trans- mission time. Philosophy of Forecast The philosophy of most forecasters working in or with tropical and sub- tropical regions is based on the premise that experience and extrapola- tion are the most reliable tools. With the known persistence of fea- tures in these regions, a careful and well-considered analysis is of prime importance. The goal is to produce an operational chart that can be readily interpreted by dispatchers and flight crews, as well as to serve as a briefing guide for pilot briefer personnel. The primary con- cern is to produce charts that will depict the wind, temperature, and significant weather over a given flight route at a given time. Depiction 1. Solid lines with arrowheads depict streamlines, generally south of 30° N latitude. To the north of 30° N, solid lines labeled by hand-stamps in geopotential decameters (thousands digit omitted at 200 mb) depict height contours. Contour intervals are 60 meters at 500 mb and 120 meters at 300 mb and 200 mb. Height centers are indicated by stamped high and low symbols. 2. Isotachs are drawn as short-dashed lines at 20 knot intervals up to 140 knots and 40 knot intervals above 140 knots labeled by stamps in knots. "Spot" winds are indicated by arrows with barbs, for 400 mb on the 500 mb chart and for 250 mb on the 300 mb chart. WBFH NO. ? ISSUANCE 67-1 10-1-67 6-60 3. Encircled "spot" temperatures are stamped on the charts in sufficient density to delineate the thermal field. 4. Heavy long-dashed lines indicate the intersections of the tropopause with constant pressure surfaces at 50 mb intervals at and below 150 mb to 400 mb, appropriately labeled in millibars, on the com- posite 200 mb/tropopause chart. Mean tropopause temperatures are entered in boxes along these lines. 5. Composite surface/significant weather 500-150 mb prognosis: a. Fronts are depicted in the usual manner (appendix 2). Isobars are drawn as solid lines labeled in millibars. Pressure cen- ters are indicated by stamped high and low symbols. b. Areas of cirrus clouds and clouds associated with significant weather are enclosed by scalloped lines and labeled by eighths of coverage and type. c. Turbulence areas are enclosed by heavy broken lines and labeled by symbols ( ^A_ moderate and _^V_ severe) . "Spot" symbols may be used also. d. Icing is indicated by appropriate symbols ( 80% Stratocumul if orm -3 WBFH NO. J ISSUANCE 67-1 101-67 3. SIZE OF FEATURES Cloud Size (Nautical Miles) Open Spaces 1 0-30 6 2 30 - 60 7 3 60 - 90 8 4 90 - 120 9 BOUNDARIES Major cloud system Definite + -|--}--|-4-4--t--}- Limit of sn ow or ice ■ Indefinite 5. PATTERNS AND SYNOPTIC INTERPRETATIONS y Point toward which cloud band(s) tend to spiral. 9 Point in a generally open field of cumuliform clouds toward which cloud elements tend to spiral Distinct comma shaped cloud mass. & A\ /Z\ &\ Cloud line (form may be ^SS_ CO l£U) ™^ &h fQ~\ dSfcl Cloud line, tenuous, Q /n/\ fa Change of element size along cloud line as indicated. WBFH NO. ? ISSUANCE 67-1 10-1-67 8-4 -^ Striations Striations , tenuous SSSS5 Wave clouds (mountain or transverse) Estimated location of the jet "X D irection of Cirrus Shear Bright (highly reflective cloud mass) Thin 5-5 WBFH NO. 1 ISSUANCE 67-1 101-67 NA-1A; DIGITIZED MOSAICS Prepared from all available data, 1:20 million polar stereo- graphic for areas 15°N latitude to 90°N latitude and from 15°S latitude to 90°S latitude, 1:20 million Mercator from 30°N latitude to 30°S latitude. Description Digitized mosaics (see appendices 41, 42, 43, 44) are facsimile pro- ducts with dimensions 18" wide by 23" long for Mercator Sections and 18" wide by 14" long for Polar Sections. They appear similar to news- paper half-tone photographs except they are in sepia and white shades where Alden paper is used. The difference between nephanalyses and digitized mosaics is shown in appendices 36 and 37. The digitized mosaics are cloud depictions made from television camera signals ob- tained from satellite passes. The television camera elements from each picture are computer processed to eliminate redundancy, adjust bright- ness, and add longitude and latitude information. The initial portion of each mosaic contains about one inch of seven or eight level tone wedge to be used for facsimile receiver calibration. The digitized mosaics complete the remainder of the chart. Date of the mosaic and geographical orientation are determined by the statement at the top of the transmission. The polar sections have, in addition, a mean time which refers to the geometrical center of the chart. The latitude and longitude lines are subdivided every 5 degrees. (Since the maximum resolution in the video picture is a function of the number of raster lines per total distance spanned, the selection of the number of samples along each raster line is made to correspond with the number of raster lines to maintain uniformity in the image. Thus, in the AVCS (Advanced Vidicon Camera System) which has 800 scan lines vertically, 800 samples are taken along each raster line to give an 800 X 800 array of 640,000 samples.) Processing Procedures Pictures are normally stored on a tape recorder on board the satellite until the next time it is interrogated by a Command and Data Acquisi- tion (CDA) Station. They may also be taken when the satellite is in range of a station, hence, are received immediately. The CDA stations are located at Gilmore Creek, Alaska, and Wallops Island, Virginia. The CDA stations interrogate the satellite and record the data on mag- netic tape. These taped signals are then transmitted to the National Environmental Satellite Center (NESC) , Suitland, Maryland, where they are fed into the CDC 6600 computer for digital rectification procedures. These involve a series of complex steps to condition the signal for sig- nal rectification and spatial rectification. a. Signal Rectification This process begins by removing certain non-earth viewing samples at the edge of each frame. Additional cropping is done within WBFH NO. ? ISSUANCE 8-7 67-1 10-1-67 each frame to minimize the sun glint problems and to avoid using imagery having poor brightness response. Noise and reference marks are removed and interpolative video information is inserted. The data are further conditioned by a brightness calibration pro- cess which includes: 1) correction for vignetting due to optical properties of the lens system, and non-linearities within the vidicon tube and associated electronics system, 2) illumination variation due to solar angle. The raw video data ranges in grey scale from to 63 which is com- pressed to a 0-14 scale in a normalizing procedure to make the grey scale display more uniform. Brightness is normalized for each frame in order to provide a reference level for establishing an uniform brightness response. The cropping and brightness nor- malizing minimizes small discontinuities that appear where frames are joined and/or at the adjoining edges of the passes. These are usually very small and hardly noticeable. b. Spatial Rectification The video data are now ready for transportation to arrays oriented to map projection. The actual rectification process is, in effect, the assignment of raster elements to earth coordinates, for replot- ting latitude and longitude values are computed for approximately every 60 miles N.M. (at the equator) for data derived from the raster lines or every 32nd sampling point along the raster line and every 32nd raster line. Once the earth coordinates have been identified and assigned within the machine grid, the intervening intervals between grid points are assumed to be linear. The re- sulting errors are small compared to uncertainities and errors found elsewhere in the system. In the next step, the video data are stretched or distorted over the large arrays (4096 grid squares for every NWP grid square) to fit a particular map projection. A linear map resolution is approximately 2 N.M. at the equator and 4 N.M. at the pole. The size of the received copy and the number of lines per inch reproduced by the facsimile recorders determines the actual resolution of the received mosaics. A map scale of 1:15 M as received on the Alden 19" facsimile recorder approxi- mates the true resolution of the original data; for a 1:20 M the resolution is lower. REFERENCE: 1. Bristor, C. L. , Callicott, W. M. , and Bradford, R. E., "Operational Processing of Satellite Cloud Pictures by Computer", MWR Vol 94, No. 8, August 1966, pp. 515-527. WBFH NO. J ISSUANCE 67-1 10-1-67 NA-2; SATELLITE ICE CHART Satellite Ice Reconnaissance Chart of the Great Lakes area at 1:2 million scale for transmission (see appendix 51 at 1240Z, 1-3 times per week depending upon cloud cover, satel- lite performance and whether or not significant changes in coverage have been observed. Processing Procedures Operational prints (5" X 7") received from each satellite pass over Great Lakes region are examined daily (or as often as region is photo- graphed) for evidence of ice in the Lakes. When ice is detected, en- larged (8" X 10") gridded photographs are obtained and analyzed. Com- posite charts are prepared from pictures acquired over a 1-3 day period and transmitted if changes are significant from last chart sent. Analysis Procedures Chart shows ice boundaries, and a four stage breakdown of apparent ice concentration. The fraction x/y (i.e., relative brightness/apparent concentration) is used by the analyst as a means of expressing as much information about satellite-observed ice characteristics as possible without stating ice age, thickness or type. In certain cases, however, the analyst will indicate in plain language when the ice appears to con- sist of small or large floes or ice fields and when and where cracks, leads, or other open water features appear. Philosophy of Analysis Charts are intended to complement or supplement, where feasible, surface and aerial observations of ice in the Great Lakes on an operational basis. As a research tool they are intended to depict total ice cover over the entire lakes region at one-to-three day intervals, if such coverage is obtainable. Depiction Non-standard notation to dapict ice concentration varying from 1-10 tenths is to be used. See legend of attached chart in appendix 51. WBFH NO. J ISSUANCE *-9 67-J 101-67 APPENDIX APPENDIX 9-1 W6FH NO. i 67-7 ISSUANCE 10-1-67 Appendix 2 WBAN WEATHER ANALYSIS SYMBOLS These are the symbols most generally used by the National Meteorological Center although there are occasionally others. ^ ^ ^ V V V I A COLD FRONT COLD FRONT ALOFT WARM FRONT STATIONARY FRONT OCCLUDED FRONT COLD FRONTOGENESIS <^ <^» -^ WARM FRONTOGENESIS A A A STATIONARY FRONTOGENESIS ^ -^ A COLD FRONTOLYSIS — ^ — ^ — ^ — WARM FRONTOLYSIS — ^ — ^ — ^ — STATIONARY FRONTOLYSIS — -^ — ^ — <•> — OCCLUDED FRONTOLYSIS — -^ — ^ — a. — INSTABILITY (SQUALL) LINE TROUGH — — — — — RIDGE /VWVVVVWVWVX NMC SURFACE PLOTTING MODELS ,D S V S © TT> 'C H pp WW ® + ppa T d T d C L (T S T S SHIP w d P H w REVISED JAN 1967 Appendix 2 WBFH NO. 1 67? ISSUANCE 10-1-67 9-2 ~ APPENDIX 3 CO >$ O Z> CMSih cvjss; oo Q. o O O O o CO -_ lOf ro . W Es co J „ co j, rO w ro . £ / ' E £ BE CD 5 Os = OJ in 1 ID & a H 1 o- CD - u 4 S v .0 : o 8 'o r-H T3 E- s.i ; Bis sals ; = =SaS3S£S. i i fl3 I;! Alii ills, 5 s s- l 5 Ui 1 5 sllll! Es is =£: if if Ssl II I- " Ej 5J II 511 13 □ £ cii is rj* 5 £ * * £ S* I" °f 1 o « SO 3? S II o _I o _l o I o- - - 2j« J. u I? a ? t ." Ilt.Ili?h g aS. SdiSo CO >< HZ n 11 * III = 1 B 11 Es E £ |s| ill JE" III |S» llf «; e Sp E « 1- * 5 31 E »« 5: is e| s| 1| 4£ i i I s f 61 Q_ < £1 il s o > £ o o o o o °=o l-S 0. CMS *' CM C\J 01 8° to rO ro ro cn cn cr> 182 9-3 WBFH NO. 1 ISSUANCE 67-1 10-1-67 X -O X ^Appendix 4 Appendix 4 9-5 WBFH NO. 1 671 ISSUANCE 10-1-67 Appendix 5 WEATHER DEPICTION GUIDE -SYMBOLIC S EC ^~r\r>t\\ j 1 lUINI STATION MODEL (1) Significant W (2) Visibility 3 R F Q- 15 (4) Ceiling he (1) SIGNIFICANT WEATHER eather — (3) Total sky-cover . . /or height of lowest '9 /scattered layer (2) VISIBILITY PLOT A A 1 Values over 6 miles will not be plotted. TRW TR sw,sp---sw (3)T0TAL SKY-COVER RW RW E E S,SG,IC---S ZR ZR R R ZL ZL L L , Always plotted, but y not more than two types. O CLEAR O SCATTERED O BROKEN O BINOVC OVERCAST F,GF, IF F v H H' K K BS BS BD BD) Not plotted ") rhen two types >f precip reptd. Plotted only when vis m » i »»«jis 6 mi. or ► Not plotted | ess wben any "T~ precip reptd (g) OBSCURED MOTE- When -X is reported for total sky-cover © will be plotted, the absence of a ceiling height will show that the obscuration is thin or partial. (4)CEILING HEIGHT NOTE IT SHOULD SELDOM BE NECESSARY TO USE MORE THAN TWO LETTERS' TO PLOT SIG- NIFICANT WEATHER, IF THE GUIDE ISUSED CORRECTLY. GIVE PRECEDENCE TO THE HIGHEST INT. SFC. CODE NUMBER, IN 6ENER- -AL THE ORDER OF IMPORTANCE IS INSTABILITY A , T ,W SOLID OR FREEZING PRECIP E , S , Z LIQUID PRECIP R , L OTHER OBSTRUCTIONS F , H , K ONLY WEATHER OCURRING AT THE STATION, AT THE TIME OF OBSERVATION WILL BE PLOTTED, DISREGARD + ft - AND FINE DEFINITIONS (GRANULAR, NEEDLES AND PELLETS , ETC) All ceiling heights will be plotted. When total sky cover is (5 'he height of lowest sctd layer is plotted. —DIGITAL SECTION — i CLASS |, Ceiling less than IOOO feet and or visibility less than 3 miles. 2. Ceiling IOOO to 5000feet and visibility 3 miles ormore. Nothing is plotted when visibility is 3 miles or more and ceiling is above 5000 feet. IMPORTANT Clouds topping ridges should al ways be plotted ^ Appendi; K 5 WBFH NO. I 67-1 ISSUANCE 1 0^1 -67 9-6 APPENDIX 6 o z < Q < Q£ LU X < LU —I < z o < z # 9-7 APPENDIX 6 WBFH NO. 1 ISSUANCE 67-1 10-1-67 APPENDIX 7 O < < < LU CD Q£ LU X t— < LU ■5 / * / h .,_ ^ ~o , r- ""- -- "1 ^..^ / / 1 / 1 f APPENDIX 7 WBFH 67-1 NO. I ISSUANCE 10-1-67 9-8 APPENDIX 8 O) CD CD en O) OJ « o V o O O c c c "0 8) "D "D c I z Z - °- I'st-- z o m C V O O •- si (©! ^Qc icie©e ® • • - .i !^#D< w (A -w a- Jl a u_ •» * N. » in — _ O. 2 Qt- « Q- to to P £ J J & * - o o z t z £ ! i 9-9 APPENDIX 8 WBFH NO. 1 67-1 ISSUANCE 101-67 Appendix 9 SUMMARY OF ABBREVIATED WMO MODEL FOR PLOTTING UPPER AIR DATA € TT T d T d HHH Constant pressure surface height, in meters at 1000 mb through 700 mb , and decameters at 500 mb and higher pres- sure surfaces. TT Temperature in whole degrees Celsius T d T d Dewpoint temperature in whole degrees Celsius . d Wind direction indicator, to 36 com- pass points. NOTE: On the 850, 700, and 500 mb charts the station circle is blacked- in when the temperature-dewpoint spread is 5° or less, less. ^ SUMMARY OF INSTRUCTIONS FOR PLOTTING AIREP DATA BY HAND All AIREP reports will be plotted which: (1) report wind or temperature. (2) are within three hours of chart time. (3) fit the altitude limits for a constant pressure chart. Constant Limits Pr essure Level 8 000-12 000 ft. 700 mb 16 000-20 000 ft. 500 mb 27 000-35 000 ft. 300 mb 36 000-40 000 ft. 200 mb Standard Height (Tens of feet or meters) 988 ft, 1829 ft 3006 ft 3866 ft 301 meters 557 meters 916 meters 1178 meters WBFH NO. J ISSUANCE 671 10-1-67 9-10 Appendix 9 f* STATION MODELS TT OR HHH hh Direction and force of mean wind plotted at mean wind position. GGZ GGZ Time of report to nearest hour hh Altitude of aircraft in thousands of feet HHH Height of constant pressure level derived from D value plotted at reported present position in decameters SUMMARY OF INSTRUCTIONS FOR PLOTTING OF WEATHER RECONNAISSANCE DATA BY HAND All reports are plotted on constant pressure chart nearest the flight level for all times, plus or minus 6 hours from the synoptic hour. STATION MODEL TT HHH GGGGZ GGGGZ Time of report to nearest minute . HHH Height of constant pressure level in decameters. Wind direction to 36 com- pass points. Reports are plotted at position given. 9-11 WBFH NO. 1 ISSUANCE 67-1 10-1-67 Appendix 10 SUMMARY OF INSTRUCTIONS FOR EDITING AND CODING AIREP REPORTS FOR USE IN COMPUTER ANALYSIS 1. The following Weather Bureau field offices are editing and coding AIREP data into bulletin form (UANT & UAPA) for transmission to Suitland in time for the observation-plus-3+25-hour data cut-off. Anchorage Int' 1 Airport (approximately north of 40° N, northern Pacific, Alaska, and Polar) Kennedy Int' 1 Airport for North Atlantic (north of 40° N) San Juan Int' 1 Airport for North Atlantic (south of 40° N) San Francisco Int'l Airport for its High Altitude Area (eastern Pac.) Honolulu Int'l Airport for its High Altitude Area (central Pac.) 2. AIREPS reporting + 3 hours of 0000Z and 1200Z for all areas north of 20° N. For areas~south of 20° N it is 0500Z through 1700Z for 1200Z, from 1700Z through 0500Z for 0000Z. The AIREPS are selected by the duty forecasters at these 5 stations, using the following criteria: a. Compatibility with the latest appropriate constant pressure analysis . b. Location of more than 5° latitude from an ocean vessel report (unless AIREP shows a significant variation in wind tempera- ture, etc., from that at the O.S.V.) c. Reporting of both height (D-value) and wind information, if possible, since the computer analysis program gives most weight to a combined report. A wind alone will get little weight in the present analysis program. d. Fit into altitude limits for constant pressure analyses, as follows: Flight Level Analysis 3,900 to 6,000 ft. 850 mb 8,000 to 12,000 ft. 700 mb 16,000 to 20,000 ft. 500 mb 21,000 to 25,000 ft. 400 mb 28,000 to 33,900 ft. 300 mb 34,000 to 38,400 ft. 250 mb 38,500 to 42,800 ft. 200 mb 42,900 to 46,000 ft. 150 mb 51,900 to 55,100 ft. 100 mb Appendix 10 WBFH NO. ? ISSUANCE 67-1 10-1-67 9-12 ^k A special WMO code is used to transmit the bulletin in the following symbolic form: CC YQL a L a L a L L L Q GGgg h^h^D^ ddfff (QL a L a L Q L ) (STT HHH) where : CC = Message identifier letters specifying the report follow- ing is an AIREP coded in this numerical form. The dou- ble letters "CC" are always included in each individual report in the position shown in the symbolic form. Y = Day of the week (according to GMT) on which the AIREP was made . Q = Octant of the globe. L a L a L a = Latitude in tenths of a degree of the point of observa- tion. L L L = Longitude in tenths of a degree of the point of observa- tion. (The hundreds digit is omitted for longitudes 100° to 180°). GGgg = Time of observation in hours and minutes, GMT. h x h x h x = Altitude of the aircraft, in hundreds of feet, at the time of observation (i.e., ICAO flight level number). D = Type of wind being reported. H z = Hazardous phenomena encountered. dd = Wind direction, in tens of degrees, at the flight level. fff = Wind speed in knots at the flight level. L L = Latitude in whole degrees, a a & L L = Longitude in whole degrees (i.e., the hundreds digit is omitted for longitudes 100° to 180°). S = Indicator figure specifying the type of temperature and height data which follow and whether the temperature is above or below 0°C. TT = Observed temperature of the free air, or temperature re- duced to the nearest standard isobaric surface, in whole degrees Celsius. HHH = D-value in decameters, or computed height of the nearest standard isobaric surface in decameters (i.e., the tens of thousands digit is omitted). WBFH NO. » ISSUANCE 67-1 10-1-67 9-13 Appe n d lix 11 1 K- 1 ' 1 \k 1 / ( ' { '\ i 1 \J . u_ 1 % 1 / ; j\ T ' . ■ ■ *_ K / , I / ■ '' - . ! L ■ ■( 1 Cv fe i 1 r S 1 -V 1 -7 \ ■-« ,' ; ■I | r*- -. ' ' ' *_ ', 1 1 -/. ! 1 t ■ s. / s '' -ft .' I i 1 ! rr ,A. /' ^j ■ . '-. • ' 5 A- j 1 ■' ', ■'' / 1 /• 7^ ^ — . • ; ' .-J; _L " ! 7 7 "{ /. * v'-^ , — - ^ i. \ ■.. r / / ',' ' ,-f •v A '.( r \ V ■./■ •r 1 ^ 'r' J ' ' V" ■) , , ■1 1 T ''; '"" J\ l , : ^ / 'V '•/ 7 ■ \ ■v ' SI! Ss- / ..." ft V \ , **" H t'i /-., :''** -. ' "(■■ '. {' 1 ■ ■- l .- 4 s \ . -i \, '. ■ .' ■ 7 . >, > _/ p*-; f , — \ sr i A 5 i ■ 5' 5 4 5 3 S 2 S 1 5 t » » 4a 47 4 »'.-'4 5 4 4 i N 1 ; f u 9 3 9 1 ^ a 3 i.i 'ri i t i ■/ i > ^ 11 2 > ! ns ^ 2 'ftl'.20 :19 7' 7 1 t> ^ UiS 2 ". 1 - *■« - ■ 1 I I - . i -V f \ j 7 / •/.^ / ^ 1 ' r i-i' .' ■' .' 1 —^ \ :: / L j ) - ^ 1 -\" ' ■ '■-■. \ d y ^ ■. - / / • i 1 \ \" , / / / I ,' 4v ■ | 1 , \ \ 1 / / 7- ,: W: \ ^ ,\ •■ 1 \ \ ' \ < ■ ' ■ , > i - I ^ $ \ \ \ I '"/ S ■■ x - i ) \ ' V l 1 V ,\ ; ■/ ! / , - / / * ■■ ■■ ,-' ? {l' \ \ U- ^ \ L-P lr I — * ■ : i . / ) 1 1 / 1 / / ? K , £ ■y f| 9^ Lf * V \ ■ I M* p -4 f -^- \ \ - -A : 1 J- / r . / 7 / ) - ; P r ' ;- '■ ^ . \ ■ ■ ',' -'-v ] rf - . , > / 1 1 -- \ \ \ ki S V-' x (■ s ;r »A r -' ■A 'iv / ■j ft ■Vn /?' V / 1 ""A ' , | J 1 1 X * I \, \ . \- \ \ 1h ..V Jrf s> s ,-' V <". (i 7' 4 ': -A ■ "'A V / -...[ 7 ■i 1 ' r ' i \ \ \ TV I'' ? J i 't ■\ Vi j I I , •;! /7 V ; • / ^/i \ :i > \ f-'v ' \ v v ^ '-7 r 1 * 1 f. J ?r t S ■ / y ;a t / > , /( /- /. /. . , — \ v ( .-A \ . t V x /, ," : I * <-: '. ' ^ S -\ '/. / T /-.. ' >..'■ 7 ' '- ,,. \ \ \ .v ■ i / f| ! '1 ■1 ■ x 11 / , / / k - . ■- f ( v "-A / ' v , - V \ A Jj ■it \ j i It f. ^2 •■ / ■■t / T ■ . / " ""V" v - \ \ \ X v \( • \ nn t /'/■ ■ u •)■! \ A ? ^ \ ■ ■ / / « . / Li I 58 i / ' . s 5 *5 4 I ) 6 i i i ! , . 9 ■_■ ' V > 7 T 1 • 1 . \ ■ ' \ s / 1 / • ■5 i \ •V \ 40 ' 1 "J • : \ %s ■ ,- ' / ■\ -H i \ \ \ r- + ' ' i 1 \ \ . i ;■; / \ uS t ^ ' fc r r i / I f hi. 1 , \ \ 7 I »- J Appendix 11 WBFH NO. 1 ISSUANCE 67-1 10-1-67 9-14 CO 3 W )—* CO CO W CO CQ E2 w O < H O Ph o CO Q O W o H £5 O H EH ft H ft O CO H P rH cu H -P CO d (D P O 0) rH rH o o Eh rQ to o o o o 00 on o o CM eg d d oj O o o o on tO O o o o on Eh o o o O LTA Eh co o p o •H d o •H d CD U ft bO id •H CO co id o •H P Oj (D d O ■H CO CO LSI LSI o 0000 O CM O LOi CO u O -P CJ •H CD U ft bO C •r-l CO d CO c o •r-l -p CO cr OJ c o •r-l CO CO CP u bO cu i-< o co OJ § 4-1 > CO CO o o O rO N o o O rOi H to cd o to EH o on PQ < v c CO rJ pq •H < u (D ft ft IP to EH o H ■d H o O P PQ flj S CVI § p ctf CT) O O tUJ P (VI .0 a) rH P ft p> cd P bi) P> ,CJ ■H rd b!) CU b() •H W ■H a; a) W H crt W rH •H CO M -p CO | •H CU CVI a ^ H H 000 OJ o 00 o H OJ oonftOJ to to to fl) H ■d > H CI cu CO CD a; rH ^ 3 n p cri p rH rd CU bi) ft •H S CU CO W ^ H H tO En 9-15 Appendix 12 W8FH NO. 7 ISSUANCE 67-7 70-7-67 Appendix 13 t-l^i-mjL— X-** - VVBFH NO. I ISSUANCE 67-1 10-1-67 Appendix 13 9-16 <• Appendix 14 < u. '■=> 10 \" Appendix 9-17 WBFH NO. I ISSUANCE 67-1 10-1-67 FA. MAP NO 6 3 £A u. Ovi O o o o O o o o O Appendix 15 C AREA D STATIONS a UPPER AIR WBFH NO. J ISSUANCE 67-1 10-1-67 9-18 3-19 PACIFIC AREA WITH SELECTED STATIONS FOR SURFACE 8 UPPERAIR Appendixl5 WBFH NO. I ISSUANCE 67-1 1°-'^ 7 WBFH NO. I ISSUANCE 67-1 10-1-67 9-20 Appendix 17 SURFACE AND THICKNESS PROGNOSIS Figure 1 in this appendix indicates the flow of prognostic products along with the principal charts and tools used in the preparation of the prog- noses . Forecast Procedures SURFACE PROGNOSES 1. TOOLS AVAILABLE: a. Initial surface, 500 mb, 1000-503 mb thickness, and 500 mb analyses. b. 3 and 12 hourly surface and 12 hourly 500 mb tendencies. c. Past history. d. NWP 500 mb, 500 mb vorticity, and advection of 500 mb vorticity by 500 mb pattern. e. The empirical and physical atmospheric relationships listed in the upper left-hand side of figure 1. These provide the forecaster with a means of producing a sur- face prognosis internally consistent with a given 500 mb prognosis . Additional information useful to the surface prognosis is provided by the climatology of mountains, normal storm tracks, and cyclogenesis . Objective computations devised by J. J. George (1), Ostby-Veigas (2), and Riehl-Haggard (3) are used more or less routinely. Reference (1) contains a comprehensive system of objective computations. Of these, NMC has found the one dealing with the deepening of east coast cyclones to be most useful. The Ostby-Veigas computation also provides forecasts of east coast cyclogenesis. 2. PREPARATION: a. A thorough study of existing relationships between sea level, 500 mb , 1000-500 mb thickness, and 500 mb vorticity is made. Points to be especially noted are: Appendix 17 WBFH NO. 1 ISSUANCE 9-21 67 .j 101-67 o c u c o CC li o> c a> F o M " > - 00 en <_ 10 ■». X — t o x 6 ~ -C to n >~ ro Q_ j: o -Q <-> "O c Si II 0) si- *s & S sr> .se -o i? E J5$ CC CD c a> E J? ro a) — X) — o rsi in m , in .9 S E 2 UJ H- O .0 -4 w a) §$fc 05 c\J o - c (1) >-, IU CO c Q. F '5 c u 0> 0. 1> c >"x : : C= lllllll D = Area of rising motion subtracted by B labeled B Area of rising motion subtracted by C labeled C £ = position of forecast 500mb vorticity maximum © = position of forecast surface cyclone A p p 6 n Q I X \7 9-31 WBFH NO. ? ISSUANCE 67-1 101-67 Appendix 20 QUANTITATIVE PRECIPITATION FORECAST (QPF) Forecast Procedures 1. TOOLS AVAILABLE: a. Vertical motion. 1). Empirical (warm advection) . 2). Sutcliffe equation. b. Precipitable water. c. Humidity. d. Stability. 2. PREPARATION: a. Computation of vertical velocities at beginning and end of forecast period. The principal indicator of vertical motion is the advection of the 1000-500 mb thickness field by the 1000 mb geostrophic wind. The sign of the vertical motion is determined by the sense of this advection and the magnitude by the areas of the quadrilaterals formed by the intersections of the isopleths of 1000 mb and 1000-500 mb thickness. The areas of the quadrilaterals, converted to what are called warm advection units (W.A.U.), have been empirically correlated by the QPF section to the precipitable water between 1000 and 500 mb and the 6-hourly precipitation amount. The scale used in measuring areas and the correlations are shown in figure 1. The computation of the initial indicated warm air advection is made from a 3-hour 1000 mb prognosis and the 12-hour barotropic prognosis. Specifically, for the QPF verifying at 12 GMT this would be a 3-hour 1000 mb prognosis from 09 GMT and the 12-hour barotropic prognosis from 0000 GMT. The computation at the end of the 24-hour period is made from the appropriate National Appendix 20 WBFH NO. 7 ISSUANCE 67-7 70-7-67 9-32 W.A.U. AREA OF QUADRILATERAL LATITUDE * 30 # 35* 40* 45 # 50° 0.5 120 87 61 47 36 1 62 44 31 24 18 1.5 31 22 16 12 9.5 2 16 II 7.8 5.9 4.5 3 II 74 5.2 3.9 3.0 4 8.0 5.5 3.8 2.9 22 5 6.4 4.4 3.1 2.3 1.7 6 5.4 3.7 2.6 2.0 1.5 7 4.6 3.2 2.2 1.7 1.3 * 2 00ft. contours PRECIPITABLE WATER 6HR PRECIP AMT PER W.A.U. .25 INCH .05 .50 .09 .75 .13 1.00 .18 1.25 .24 1.50 .31 1.75 .39 2.00 .50 MEASURING SCALE FOR QUADRILATERALS. UNITS 1° OF LAT. AT 40° N ON POLAR STEREO- GRAPHIC PROJECTION. TRUE AT 60°. SCALE 1:20,000,000 I 2 3 4 5 6 7 8 9 10 II 12 13 14 15 Figure 1 Weather Analysis Center, 1000 mb and 1000-500 mb thickness prognoses. The computations are made at discrete points, and then isopleths of W.A.U. are drawn. b. Evaluation of duration and intensity of W.A.U. for 24-hour period . In cases where there is continuity of movement of the warm advection areas, duration and intensitv is determined by graphi cal linear interpolations. The simplest case is a warm advec- tion area that remains stationary and of the same intensity for 24 hours. In other instances, intermediate patterns of warm advection are drawn in order to determine graphically the duration and intensity. If a new warm advection area is fore- cast, a subjective evaluation of when it first appears during the period must be made. 9-33 WBFH NO. 1 ISSUANCE 67-1 10-1 -67 » c. Forecast of precipitable water. This step is primarily subjective. Heavy reliance is placed on the initial distribution of precipitable water, an approxi- ' mation for which can be obtained in areas of precipitation by noting the saturation value of the initial 1000-500 mb thick- ness obtained in step (a) in these areas. Continuity is used. When appropriate, advection of the precipitable water by the 850 mb wind is used. However, advecting a quantity that is integrated through a layer 500 mb thick, can become a highly complicated operation. d. Computation of precipitation amounts. In cases when the area of warm advection is associated with precipitation at the initial time, this is accomplished simply by using the results of steps (b) and (c) and entering the lower left hand table of figure 1. One of the most difficult problems which is well-known to all forecasters is when pre- cipitation will begin in a previously dry system. To help with this problem, a relative humidity chart of the layer between 1000 and 500 mb is used. The relative humidity is obtained by dividing the actual precipitable water by that which could be held by a saturated standard atmosphere corresponding to the observed 1000-500 mb thickness. Subjective estimates are made concerning the onset of precipitation using the relative hu- midity chart and the indicated warm advection. A rough objec- tive guide is, that one W.A.U. will increase the relative hu- midity 15% in 12 hours. SUMMERTIME QUANTITATIVE PRECIPITATION FORECASTING The physical logic of the system just described, breaks down when ap- plied to summertime precipitation. At the same time, the system is useful. It is useful because the meso-scale precipitation patterns of summer usually occur in areas where the macro-scale vertical motion is favorable. Not much further can be said about summer quantitative pre- cipitation forecasting, except to note that stability and moisture are considered more closely, and synoptic experience plays a greater role in the success of the forecast than is the case in winter. WBFH NO. 1 ISSUANCE 67? 101-67 9-34 APPENDIX 21 9-35 APPENDIX 21 WBFH NO. 1 ISSUANCE 671 7 0-1-67 Appendix 22 FOR PERIOD 22 1200ZTO 231200Z Boundary of Thunderstorm Area (storms expected to right o\ line) Instability (Squall) Line i ■ i i. , Severe Thunderstorm Are Tornado Area WBFH NO. 1 ISSUANCE 67-1 10-1-67 v ■ 9-36 r Appendix 24 Appendix 24 9-37 WBFH NO. 1 ISSUANCE 67-1 10-1-67 WBFH NO. 7 ISSUANCE 671 10147 9-38 % 9-39 WBFH NO. ? ISSUANCE 67-7 101-67 APPENDIX 26 a ? s - s 1 s ■■'" J- CM Q. =1 5 > Q a S I u •- a.' a 5 e „ U — * a CdO <0- APPENDIX 26. WBFH NO. ? 67-1 ISSUANCE 10-1-67 9-40 t Appendix 27 PRESENTATION OF "ON- TIME" PRECIPITATION FORECASTS The following method of presenting "on-time" precipitation forecasts is used on all NMC short-range (i.e., 12 to 48 hour) surface prognoses. 1. A solid line is used to define areas within which the predomin- ant precipitation is forecast to result from any type of large- scale vertical motion (e.g., overrunning) or from continuous locally induced vertical motions (e.g., "upslope" flow or Gulf drizzle). These areas are used most often in winter precipita- tion situations. When equal to or greater than 50% area cover- age is forecast, these areas are stippled on the facsimile charts. When less than 50% area coverage of precipitation is forecast, these areas are left blank on the facsimile charts, except for the precipitation symbol. The forecast precipitation type will be indicated by the following symbols: Drizzle 1. Continuous Heavy 2. Continuous Moderate 3. Continuous Light , , 4. Intermittent , Rain 1. Continuous Heavy .'. 2. Continuous Moderate 3. Continuous Light Intermittent Snow 1. Continuous Heavy # ^ Continuous Moderate 4 * * 3. Continuous Light * * 4. Intermittent * Normally the symbol for continuous light precipitation is used, Occasionally, the symbols for moderate and heavy intensities may be used to conform with large amounts shown in the quanti- tative precipitation forecast. 9-41 Appendix 27 WBFH NO. I R-7-1-68 A "dashed-dot" line is used to define areas within which pre- dominant precipitation is forecast to be of convective or un- stable shower type due largely to local, small-scale vertical motions. These areas are used most often in warmer season pre- cipitation situations. Stippling is also used in presenting the area coverage of showers. That is, no stippling below 50% coverage and stip- pling for 50% or greater coverage. The type of shower activity expected is indicated by standard shower and/or thunderstorm symbols. No indication of intensity is given. The solid-line divisions within precipitation or shower areas indicate changes in area coverage, i.e., from less than 50% to 50% or more, rather than change in type or intensity. The division of frozen and non-frozen precipitation within these areas is delineated by a dashed line and the appropriate change in symbol on either side of this line. ' r WBFH NO. 1 ISSUANCE 67-1 10-1-67 9 «42 Appendix 27 I 9-43 WBfH NO. I R-7-1-68 APPENDIX 28 * APPENDIX 28 "* WBFH NO. J ISSUANCE 67-1 10-1-67 9-44 APPENDIX 29 ) APPENDIX 29 9-45 WBFH NO. 1 67-1 ISSUANCE 10-J-67 Appendix 30 700 MB >ftg3APR27*9K 'fpi t t WBFH NO. I ISSUANCE 67-1 10-1-67 9-46 Appendix 30 (• ♦ Appendix 31 / t 4 o + __+/ + +*--- 1 2 + 4 + + + + 1 V p + T 4 1 t o 4 + 4* 4 i-\ /^o^. — " — t 4 4 4 4 + £ 4 + 4 /v ^O ,-t ".'-.+ -*-''. 3 V \ + r + ,uv ^1 *v + /+ ' 1 / 4 /+ 90 Ot 1 +\ 70 <#+\ o / + + +■ + [S> 1 4 4 7 9-47 i* P(nTTFn pv NMC EFS MAP V673F POLAR STEREO. PROJECTION SCALE IS0.OO0.0O0 Appendix 31 WBFH NO. 1 67-7 ISSUANCE 70-1-67 Appendix 32 WBFH NO. 1 ISSUANCE 67-7 101-67 Appendix 32 9-4g Appendix 33 9=49 Appendix 33 iwnru i. i /~\ i iccii»kir WBFH NO. I ISSUANCE 67? 10-1-67 Appendix 34 72 HR SFC PROG V T. 12Z THURSDAY MAR 3 1966 TEMP ANOMALY Appendix 34 A WBfH NO. 1 ISSUANCE 67-1 70-1-67 9-50 Appendix 35 9-51 WBFH NO. 1 ISSUANCE 67-1 10-1-67 WBFH NO. J ISSUANCE 671 10-1-67 9-52 Appendix35 APPENDIX 36 APPENDIX 36 WBFH NO. 1 ISSUANCE 67-1 10-1-67 9-53 APPENDIX 37 WBFH NO. I ISSUANCE 671 10-1-67 APPENDIX 37 9-54 Appendix 39 SCHEMATIC DIAGRAM OF STRUCTURE OF 6-LAYER (PE) NUMERICAL PREDICTION MODEL P = QUIET CAP OR LAYER WHERE Q IS CONSTANT v O 4 Kl Kl NNhOO ON 00 h- PC CM CM CM CM CM CM CM CM i-H r-H r-H r-H •— 1 r-H i-H H r-H p-H r-H 1 vt PS r-- t-- \o no m ■* 4 Kl CM H r-H O ON in m m in m in in in in in m m oo cm HI HI r-~ no m <* hi >J § NO nO nO nO nO \0 >0 O N h t^ oo oo £ w CM CM CM CM CM CM CM CM CM CM CM CM CM H + + + + + + + + + + + + + w rJ < CO o o o o o o o o o o o o o w CQ O ON oo r-~ no m N_> 0) r-H in

CO CO CD CM .H O 3 P - CD CO !h C <» o, o P x: V o. +-> >> P ■a c c a ■r-l /-\ - a £u N^ •rH J= 00 01 +J c J= o fan •r-l •rH 4-> CO CO JC CD o « +J NO nO r~ f- 00 00 r-H l-H + + + + + + o o o o o o m l> 00 CM HI HI NO J3 xi XI XI XI 4-> e B B B B B "O o o o o o o C > CO CD I-H O c IV bO r-H CO [H CO 3 Ph en CO -Q cd" bO c p-H CD CD B •rH CO C •rH >: U •rH c ca +J CD rH •rH B C >> <0 B 0J CD e o O a p • 0) c si CO J3 £ a) p u C s ■P a o o cfl •rH •rH o >> ^ > Ih P o r-H -H CU CO t^- r-H CD bO p at £1 CD 3 •v & ■P r-H CO CU c rH r— i CD B CO O U •rH x; o Z O 3 p CJ CD rH p OT CO CD !h Ph r-H CO CM HI »* m NO NO u l-H r-H r-H r-H r-H ■p + + + + + + c XI XI XI X: S e B B B B o o o o o o o ON 00 f- nO in o ON ON ON ON ON WBFH NO. 67-1 ISSUANCE 70-1-67 9-74 APPENDIX 49 DESCRIPTION OF THE COMPUTER-PRODUCED 250 MB WIND FIELD FROM THE WBFC HONOLULU The 24-hour computer wind forecasts of the Tropical Pacific are made utilizing a simple statistical scheme. This scheme postulates that the tropical atmos- phere has a tendency toward return to climatological mean conditions. The rate of return is variable from point to point and can be stated in terms of a lag coefficient. Thus the forecast of the u, v wind components can be stated as = (l-r u ) u { + r u "p v F = (l-r v ) v c + r v v. Where the subscript F refers to the forecast values of u and v, the subscript c to the monthly climatic mean wind value at a point, and p to persistence, r is the component lag coefficient determined by somewhat limited records at Tropical Pacific stations. The machine output is made in the form of a machine plotted chart in which the wind data is plotted at each grid point denoted by a wind barb to show wind direction in tens of degrees and velocity in knots. (See Figure 1.) The prognoses are made twice daily for 0000Z and 1200Z on a 1:20 million scale Mercator chart extending from 75°E to 90°W and from 24°S to 37°N. (See appendix 45) Detailed information on this forecast model is available in the following references: REFERENCES : Bedient, H. A., and Vederman, J., "Computer Analysis and Forecasting in the Tropics", Monthly Weather Review, Volume 92 . No. 12, December 1964. Lavoie, R. L., and Weideranders , C. J., "Objective Wind Forecasting Over the Tropical Pacific", University of Hawaii, Institute of Geophysics, Meteorology Division; #1, Contract AF 19(604)-7229, AFCRL-TN-60-832, Dec. 1960, ^ 9-75 WBFH NO. I 671 ISSUANCE 101-67 i^cs •© oo L z ^ «>> o -. o O O CM o o m i i ... J \ \ \ N \ y J j i ^ > \ ^ vO <7i ^ ^ / / j \ \ \ \ ; " J J I \ \ \ a o O \|/ W J J J J j J J J •o o < CO cfl • o l-H QJ u °° \ V \ V I ) j J j 7 if N ■ V \ > ' ; ^ N j ' y •*" ^ j J J j j ) y ^ ^ *" <^ <^ *-" J \ i %