Winds aloft, officially known as the winds and temperatures aloft forecast, (known as "FD" in the US and Canada, but becoming known as "FB", following the World Meteorological Organization [WMO] nomenclature), is a forecast of specific atmospheric conditions in terms of wind and temperature at certain altitudes, typically measured in feet (ft) above mean sea level (MSL). The forecast is specifically used for aviation purposes.
The components of a winds and temperatures aloft forecast are displayed as DDss+/-TT:
Wind direction (DD) and wind speed (ss), displayed as a 4-digit number, e.g. 3127, indicating a wind direction of 310 degrees true north and a wind speed of 27 knots. Note that wind direction is rounded to the nearest 10 degrees and the trailing zero is excluded.
Temperature (TT), displayed as a +/- two-digit number, indicating temperature in degrees Celsius.
Above 24,000 feet, the format changes by omitting a +/- sign on temperature. Temperatures at high aviation altitudes are below zero Celsius.
Example
FBUS31 KWNO 190440 DATA BASED ON 190000Z DATA VALID 190600Z FOR USE 0600-1200Z. TEMPS NEG ABV 24000 FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 ABR 1027 1326+01 1428-03 1431-09 1639-21 1749-34 175849 175957 174758 ABI 2849+04 2857-02 2760-07 2670-20 2682-32 760344 760648 259451
ABR, ABI, and ALS are the weather station abbreviations used in this report.
Wind speeds over 99 knots are extracted by subtracting 50 from the direction and adding 100 to the speed. Thus, for example, the wind forecast for Abilene (ABI) at 30,000 feet, shown above as 7603, indicates a forecast wind of 260 degrees at 103 knots (76-50=26 or 260, and speed became 100+03=103).
This forecast is now made four times a day based on 0000Z, 0600Z, 1200Z, and 1800Z data (the Z stands for Zulu and indicates Coordinated Universal Time). The forecasts are valid 6 (FD1/8), 12 (FD2/9), and 24 (FD3/10) hours after the observation date/times of 0000Z and 1200Z upon which they are based. Depending on station elevation, FD1/2/3 wind forecasts are issued for the following levels: 3, 6, 9, 12, 18, 24, 30, 34, and 39 thousand feet.
The first level for which a wind forecast is issued is 1,500 feet or more above the station elevation. Temperature is forecast for all wind levels, except the 3,000 foot level, that are 2,500 feet or more above the station. As indicated in the third line of the forecast, the temperatures at all levels above 24,000 feet are generally negative and the minus sign is excluded. FD8/9/10 are for the 45,000 and 53,000 foot levels.
Light and variable winds (which by definition have speed close to zero and also lack specific direction) are coded as 9900.
References
NATIONAL WEATHER SERVICE INSTRUCTION 10-812 – Aviation Wind and Temperature Aloft Forecasts Instructions
NOAA's National Weather Service – Forecast Winds and Temps Aloft Help
External links
Forecast winds and temps aloft, NOAA's National Weather Service, Aviation Weather Center, ADDS Wind Temp Data page, featuring graphical and other optional presentation formats
January 18, 2023
winds, aloft, officially, known, winds, temperatures, aloft, forecast, known, canada, becoming, known, following, world, meteorological, organization, nomenclature, forecast, specific, atmospheric, conditions, terms, wind, temperature, certain, altitudes, typi. Winds aloft officially known as the winds and temperatures aloft forecast known as FD in the US and Canada but becoming known as FB following the World Meteorological Organization WMO nomenclature is a forecast of specific atmospheric conditions in terms of wind and temperature at certain altitudes typically measured in feet ft above mean sea level MSL The forecast is specifically used for aviation purposes The components of a winds and temperatures aloft forecast are displayed as DDss TT Wind direction DD and wind speed ss displayed as a 4 digit number e g 3127 indicating a wind direction of 310 degrees true north and a wind speed of 27 knots Note that wind direction is rounded to the nearest 10 degrees and the trailing zero is excluded Temperature TT displayed as a two digit number indicating temperature in degrees Celsius Above 24 000 feet the format changes by omitting a sign on temperature Temperatures at high aviation altitudes are below zero Celsius Example EditFBUS31 KWNO 190440 DATA BASED ON 190000Z DATA VALID 190600Z FOR USE 0600 1200Z TEMPS NEG ABV 24000 FT 3000 6000 9000 12000 18000 24000 30000 34000 39000 ABR 1027 1326 01 1428 03 1431 09 1639 21 1749 34 175849 175957 174758 ABI 2849 04 2857 02 2760 07 2670 20 2682 32 760344 760648 259451 ABR ABI and ALS are the weather station abbreviations used in this report Wind speeds over 99 knots are extracted by subtracting 50 from the direction and adding 100 to the speed Thus for example the wind forecast for Abilene ABI at 30 000 feet shown above as 7603 indicates a forecast wind of 260 degrees at 103 knots 76 50 26 or 260 and speed became 100 03 103 This forecast is now made four times a day based on 0000Z 0600Z 1200Z and 1800Z data the Z stands for Zulu and indicates Coordinated Universal Time The forecasts are valid 6 FD1 8 12 FD2 9 and 24 FD3 10 hours after the observation date times of 0000Z and 1200Z upon which they are based Depending on station elevation FD1 2 3 wind forecasts are issued for the following levels 3 6 9 12 18 24 30 34 and 39 thousand feet The first level for which a wind forecast is issued is 1 500 feet or more above the station elevation Temperature is forecast for all wind levels except the 3 000 foot level that are 2 500 feet or more above the station As indicated in the third line of the forecast the temperatures at all levels above 24 000 feet are generally negative and the minus sign is excluded FD8 9 10 are for the 45 000 and 53 000 foot levels Light and variable winds which by definition have speed close to zero and also lack specific direction are coded as 9900 References EditNATIONAL WEATHER SERVICE INSTRUCTION 10 812 Aviation Wind and Temperature Aloft Forecasts Instructions NOAA s National Weather Service Forecast Winds and Temps Aloft HelpExternal links EditForecast winds and temps aloft NOAA s National Weather Service Aviation Weather Center ADDS Wind Temp Data page featuring graphical and other optional presentation formats Retrieved from https en wikipedia org w index php title Winds aloft amp oldid 962711010, wikipedia, wiki, book, books, library,
