Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
7.4 Wind and Temperature Aloft Forecast (FB) Wind and Temperature Aloft Forecasts (FB) are computer prepared forecasts of wind direction, wind speed, and temperature at specified times, altitudes, and locations. Forecasts are based on the North American Mesoscale (NAM) forecast model run. FBs are available on the Aviation Weather Center (AWC) Web site at: http://aviationweather.gov/products/nws/winds/.
7.4.1 Forecast Altitudes The following table contains the altitudes for which winds are forecast. Altitudes up to 15,000 feet are referenced to Mean Sea Level (MSL). Altitudes at or above 18,000 feet are references to flight levels (FL).
Table 7- 9. Wind and Temperature Aloft Forecast Levels Actual Altitudes (MSL) 1,000 feet* 1,500 feet* 2,000 feet* 3,000 feet 6,000 feet 9,000 feet 12,000 feet 15,000 feet* Pressure Altitudes (Hectopascals) 18,000 feet (500 Hectopascals) 24,000 feet (400 Hectopascals) 30,000 feet (300 Hectopascals) 34,000 feet (250 Hectopascals) 39,000 feet (200 Hectopascals) 45,000 feet (150 Hectopascals)# 53,000 feet (100 Hectopascals)# * Hawaii and Western Pacific only.
# Not available for selected locations in the Contiguous US.
Wind forecasts are not issued for altitudes within 1,500 feet of a location's elevation. Temperature forecasts are not issued for altitudes within 2,500 feet of a location's elevation. Forecasts for intermediate levels are determined by interpolation.
7.4.2 Format The symbolic form of the forecasts is DDff+TT in which DD is the wind direction, ff the wind speed, and TT the temperature.
Wind direction is indicated in tens of degrees (two digits) with reference to true north and wind speed is given in knots (two digits). Light and variable wind or wind speeds of less than 5 knots are expressed by 9900. Forecast wind speeds of 100 through 199 knots are indicated by subtracting 100 from the speed and adding 50 to the coded direction. For example, a forecast of 250 degrees, 145 knots, is encoded as 7545. Forecast wind speeds of 200 knots or greater are indicated as a forecast speed of 199 knots. For example, 7799 is decoded as 270 degrees at 199 knots or greater.
Section 7: Forecast Text Products Page 7-39
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Temperature is indicated in degrees Celsius (two digits) and is preceded by the appropriate algebraic sign for the levels from 6,000 through 24,000 feet. Above 24,000 feet, the sign is omitted since temperatures are always negative at those altitudes.
The product header includes the date and time observations were collected, the forecast valid date and time, and the time period during which the forecast is to be used.
Examples
1312+05 The wind direction is from 130 degree (i.e. - southeast), the wind speed is 12 knots and the temperature is 5 degrees Celsius.
9900+10 Wind light and variable, temperature +10 degrees.
7735-07 The wind direction is from 270 degrees (i.e. west), the wind speed is 135 knots and the temperature is minus 7 degrees Celsius.
7.4.2.1 Coding Example Sample winds aloft text message:
DATA BASED ON 010000Z VALID 010600Z FOR USE 0500-0900Z. TEMPS NEG ABV 24000 FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 MKC 9900 1709+06 2018+00 2130-06 2242-18 2361-30 247242 258848 550252 Sample message decoded:
(Line 1) DATA BASED ON 010000Z Forecast data is based on computer forecasts generated the first day of the month at 0000 UTC.
(Line 2) VALID 010600Z FOR USE 0500-0900Z. TEMPS NEG ABV 24000 The valid time of the forecast is the 1st day of the month at 0600 UTC. The forecast winds and temperature are to be used between 0500 and 0900 UTC. Temperatures are negative above 24,000 feet.
(Line 3) FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 FT indicates the altitude of the forecast.
(Line4) MKC 9900 1709+06 2018+00 2130-06 2242-18 2361-30 247242 258848 550252 MKC indicates the location of the forecast. The rest of the data is the winds and temperature aloft forecast for the respective altitudes.
The following table shows data for MKC (Kansas City, MO).
Section 7: Forecast Text Products Page 7-40
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Table 7- 10. Wind and Temperature Aloft Forecast Decoding Examples FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 MKC 9900 1709+06 2018+00 2130-06 2242-18 2361-30 247242 258848 550252 Altitude (feet) Coded Wind Temperature (oC) 3,000 FT 9900 Light and variable Not forecast 6,000 FT 1709+06 170 degrees at 9 knots +06 degrees Celsius 9,000 FT 2018+00 200 degrees at 18 knots Zero degrees Celsius 12,000 FT 2130-06 210 degrees at 30 knots -06 degrees Celsius 18,000 FT 2242-18 220 degrees at 42 knots -18 degrees Celsius 24,000 FT 2361-30 230 degrees at 61 knots -30 degrees Celsius 30,000 FT 247242 240 degrees at 72 knots -42 degrees Celsius 34,000 FT 258848 250 degrees at 88 knots -48 degrees Celsius 39,000 FT 750252 250 degrees at 102 knots -52 degrees Celsius
7.4.2.2 Example for the Contiguous US and Alaska DATA BASED ON 091200Z VALID 091800Z FOR USE 1400-2100Z. TEMPS NEG ABV 24000 FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 ABI 1931+10 1929+10 2024+06 2331-10 2448-23 235239 246348 256056 ABQ 2213+03 2327-04 2253-17 2263-27 227242 236946 245749 ABR 2017 2312+14 2308+09 2615+02 2724-13 2527-26 273641 274051 274562 AGC (etc.)
FT 45000 53000 ABI 301049 281149 ABQ 235061 244859 ABR 224559 243756 AGC (etc.)
Note: 45,000- and 53,000-foot winds are not available for selected locations in the conterminous US.
7.4.2.3 Example for Hawaii and the Western Pacific DATA BASED ON 091200Z VALID 091800Z FOR USE 1400-2100Z. TEMPS NEG ABV 24000 FT 1000 1500 2000 3000 6000 9000 12000 15000 18000 24000 LIH 9900 9900 1705 1806 1711+13 2216+10 2520+05 2523+01 2833-07 2937-19 HNL 9900 9900 9900 9900 1407+14 1908+11 2410+05 2612+01 2928-07 2930-18 LNY 9900 9900 9900 9900 1208+14 9900+11 9900+06 2909+01 3024-07 3027-18 OGG (etc.)
FT 30000 34000 39000 45000 53000 LIH 040734 990044 241055 281666 990072 HNL 051234 010543 250654 301066 990072 LNY 041433 010743 230754 260966 990072 OGG (etc) Note: The altitudes forecast in the Hawaii and western Pacific bulletins are different than those forecast in the Contiguous US and Alaska Note: The Hawaii and western Pacific bulletins are separated at the 24,000 foot level instead of 39,000 feet because of the additional, lower levels noted in Table 7-8.
Section 7: Forecast Text Products Page 7-41
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
7.4.3 Issuance The NWS National Centers for Environmental Prediction (NCEP) produces scheduled Wind and Temperature Aloft Forecasts (FB) four (4) times daily for specified locations in the Continental United States (CONUS), the Hawaiian Islands, Alaska and coastal waters, and the western Pacific Ocean (Figures 7-8 through 7-11).
Amendments are not issued to the forecasts.
TO SEA CAST *PDXYKM GECFCA TEMLEEGR *OTH RDM *IMB LWS •GTF •GGW «MOT GFK INL DLH MOT SSM *PLB PWM BOS "LN •BIL MLS DIK SYR ALB BACK FOT SIY LKY •BOI *MSP GRB •MKG ECK BUF AVA JFK BOL
• SFO •RBL SACRNO BAM "FAT CELY "SLC RKS •PIM LND •GJT DEN GLD SLN MKC MBW BFF •CZI CRAP PIR •ONL "GRI OMA DSM CFSD MCWOBO OLSE TBRL OUSTL EVYLOU •CRR •SPI IND "JOT „FWACMHAGC EMI • CVG SCLE PSB CACY PEKN RIC ORF SBA LAS •BCE *FMN ALS +PUB •GCK ICT •S&F" CO BNA TVS •TRI 'RDU HAT
•W.JF SILM *SAN BLH *PRC • ONT •PHX ZUN ABO TCC AMA •OKC FSM + GAG + TUL •LIT " MEN HSV «BHM ATL -GSP "FLO •CAE
• TUS HELP INK ABI «DAL SHV JAN "MGM «ROW-LBB "SPS CSG JJAX °2XG YSAV
•MRF •SAFPSX •T01•TO6 "TO7 "4J3 PIE: ° CLL LCH MSYMOE PFN SHOU ATLH AMLE + H61 MIA 1
LRD CRP
•H52 SEYW BRO °H51 Figure 7-8. Wind and Temperature Aloft Forecast Network - Contiguous U.S.
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Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010) 70i
•BRW:
Вт LUR COTZ AFM #BTT *FYU COME • GAL + FAI SUNK 60 CZF * MCG aTKA GKN ORT LANC ¿BET CHOM *MDO ISNP ЛЕНИ LAKN •5ĄG 55 LADO
• 5AB +5АP FANN SAE ADK. - + 5AD -180 -170 -160 -150 -140 ₴5AC -130 Figure 7-9. Wind and Temperature Aloft Forecast Network - Alaska 22 rOGG NY 20
I KOA ITO .:160 .:158 156 Figure 7-10. Wind and Temperature Aloft Forecast Network - Hawaii Section 7: Forecast Text Products Page 7-43
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Figure 7-11. Wind and Temperature Aloft Forecast Network – Western Pacific Section 7: Forecast Text Products Page 7-44
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Table 7- 11. Wind and Temperature Aloft Forecast (FB) Periods Model Run Product Available 6 hour Forecast 12 hour Forecast 24 hour Forecast Valid For Use Valid For Use Valid For Use 0000Z ~0200Z 0600Z 0200-0900Z 1200Z 0900-1800Z 0000Z 1800-0600Z 0600Z ~0800Z 1200Z 0800-1500Z 1800Z 1500-0000Z 0600Z 0000-1200Z 1200Z ~1400Z 1800Z 1400-2100Z 0000Z 2100-0600Z 1200Z 0600-1800Z 1800Z ~2000Z 0000Z 2000-0300Z 0600Z 0300-1200Z 1800Z 1200-0000Z
7.4.4 Delayed Forecasts If the scheduled forecast transmission is delayed, the existing valid forecast based on the earlier 6-hourly data can be used until a new forecast is transmitted.
Section 7: Forecast Text Products Page 7-45
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
FORECAST CHARTS Short-Range Surface Prognostic (Prog) Charts Short-Range Surface Prognostic (Prog) Charts (Figure 8-1) provide a forecast of surface pressure systems, fronts and precipitation for a 2-day period. The forecast area covers the 48- contiguous states, the coastal waters and portions of adjacent countries. The forecasted conditions are divided into four forecast periods, 12-, 24-, 36-, and 48-hours. Each chart depicts a “snapshot” of weather elements expected at the specified valid time.
The Surface Prognostic (Prog) Charts are available at the Aviation Digital Data Services (ADDS) Web site.
Figure 8-1. Surface Prog Chart Example
Section 8: Forecast Charts Page 8-1
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
8.1.1 Content
- COLD FRONTOLYSIS
• WARM FRONTOLYSIS STATIONARY FRONT • STATIONARY
FRONTOLYSIS
OCCLUDED FRONT
- OCCLUDED FRONTOLYSIS
CHANGE OF FRONT TYPE
COLD FRONTOGENESIS HIGH PRESSURE CENTER
WARM FRONTOGENESIS LOW PRESSURE CENTER
STATIONARY TROPICAL (TRPL) WAVE
FRONTOGENESIS TROUGH (TROF) OR L xxx XXX TROPICAL DEPRESSION
OUTFLOW BONDARY (OUTFLOW BNDRY)
TRPCL STORM TROPICAL STORM
DRYLINE XXX
RIDGE HURCN HURRICANE
SQUALL LINE XXX Figure 8-2. Surface Prog Chart Symbols
8.1.1.1 Pressure Systems Pressure systems are depicted by pressure centers, troughs, isobars, drylines, tropical waves, tropical storms and hurricanes using standard symbols (Figure 8-2). Isobars are denoted by solid thin gray lines and labeled with the appropriate pressure in millibars. The central pressure is plotted near the respective pressure center.
8.1.1.2 Fronts Fronts are depicted using the standard symbols in Figure 8-2.
8.1.1.3 Squal Lines Squall lines are denoted using the standard symbol in Figure 8-2.
8.1.1.4 Precipitation Rain (light, moderate,heavy) ** Snow (light, moderate, heavy) R K Thunder (with rain, snow,no precipitation) Shower (rain, snow) Drizzle ~ Freezing rain, Freezing drizzle Ice pellets/Sleet Fog (shallow, deep) 00 Haze Figure 8-3. Surface Prog Chart Precipitation Symbols Section 8: Forecast Charts Page 8-2
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Precipitation areas are enclosed by thick, solid, green lines (Figure 8-4). Standard precipitation symbols are used to identify precipitation types (Figure 8-3). These symbols are positioned within or adjacent to the associated area of precipitation. If adjacent to the area, an arrow will point to the area with which they are associated. A mix of precipitation is indicated by the use of two pertinent symbols separated by a slash (Figure 8-4). A bold, dashed, grey line is used to separate precipitation within an outlined area with contrasting characteristics (Figure 8-4). For instance, a dashed line would be used to separate an area of snow from an area of rain.
Figure 8-4. Surface Prog Chart Precipitation Example
Precipitation characteristic are further described by the use of shading (Figure 8-5). Shading or lack of shading indicates the expected coverage of the precipitation. Shaded areas indicate the precipitation is expected to have more than 50% (broken) coverage. Unshaded areas indicate 30-50% (scattered) coverage.
Figure 8-5. Surface Prog Chart Precipitation Coverage Section 8: Forecast Charts Page 8-3
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010)
Issuance Short-Range Surface Prognostic (Prog) Charts are issued by the Hydrometeorological Prediction Center (HPC) in Camp Springs, MD. Table 8-1 provides the product schedule. The 12- and 24- Hour Surface Prognostic (Prog). Charts are issued four times a day and are termed “Day 1” progs. The 36- and 48- Hour Surface Prog Charts are issued twice daily and are termed “Day 2” progs. They are available on the HPC Web site.
Table 8-1. Short-Range Surface Prog Charts Schedule Issuance Time (UTC) ~1720 ~2310 ~0530 ~0935 Valid Time (UTC) 12-Hour Surface Prog 24-Hour Surface Prog 36-Hour Surface Prog 0000 0600 1200 1200 1800 0000 0000 NA 1200 1800 0600 NA NA 48-Hour Surface Prog 1200 NA 0000
Use Short-Range Surface Prognostic (Prog) Charts can be used to obtain an overview of the progression of surface weather features during the next 48 hours. The progression of weather is the change in position, size, and intensity of weather with time. Progression analysis is accomplished by comparing charts of observed conditions to the 12-, 24-, 36-, and 48-hour progs. Short-Range Surface Prognostic (PROG) Charts make the comprehension of weather details easier and more meaningful. For example, in Figures 8-6 through 8-9, the cold front located from the eastern Great Lakes to Missouri is forecast to move southeastward and the High pressure center just north of the Minnesota/North Dakota boarder is also forecast to move southeast and weaken.
Section 8: Forecast Charts Page 8-4
Aviation Weather Services, Advisory Circular 00-45G Change 1 (July 2010) 12-HR FOST OF FRONTS/PRESSURE AND WEATHER VALID: 0000Z FRI DEC 17 2004 10฿6 1031 H 036 0-3 TROF DOC/NORA/NWS/NCEP/HFC ISSUED: 16312 THU DEC 16 2004 Figure 8-6. 12-Hour Surface Prog Chart Example 24-HR FOST OF FRONTS/PRESSURE AND WEATHER VALID: 1200Z FRI DEC 17 2004 RO ·940 1042 TROF TROF DOC/NORA/NWS/NCEP/HPC ISSUED: 1632Z THU DEC 16 2004 Figure 8-7. 24-Hour Surface Prog Chart Example Section 8: Forecast Charts Page 8-5