Winds aloft


Winds aloft, officially known as the winds and temperatures aloft forecast,, is a forecast of specific atmospheric conditions in terms of wind and temperature at certain altitudes, typically measured in feet above mean sea level. The forecast is specifically used for aviation purposes.
The components of a winds and temperatures aloft forecast are displayed as DDss+/-TT:
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 at 30,000 feet, shown above as 7603, indicates a forecast wind of 260 degrees at 103 knots.
This forecast is now made four times a day based on 0000Z, 0600Z, 1200Z, and 1800Z data. The forecasts are valid 6, 12, and 24 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 are coded as 9900.