AWC - Forecast Winds and Temps Aloft Help

Forecast Winds and Temps Aloft Help

The former "FDWinds" products are now issued as "FBWinds". See all the related changes in the NWS directive (PDF):

NWS Aviation Winds and Temperatures Aloft Forecasts

Winds Aloft forecast periods

Data available	Model Run	6 hour ‘FOR USE’ times	12 hour ‘FOR USE’ times	24 hour ‘FOR USE’ times
~0200 UTC	0000 UTC	0200-0900 UTC *	0900-1800 UTC *	1800-0600 UTC
~0800 UTC	0600 UTC	0800-1500 UTC *	1500-0000 UTC *	0000-1200 UTC
~1400 UTC	1200 UTC	1400-2100 UTC *	2100-0600 UTC *	0600-1800 UTC
~2000 UTC	1800 UTC	2000-0300 UTC *	0300-1200 UTC *	1200-0000 UTC

Note *: Change in FBWinds “For Use” times. See TIN for details.

Navigation

Format

Winds aloft are computer prepared and contain forecast wind direction and speed as well as forecast temperatures. The standard FB levels are as follows:

Low Level

3,000 feet
6,000 feet
9,000 feet
12,000 feet
18,000 feet
24,000 feet
30,000 feet
34,000 feet
39,000 feet

1,000 feet
1,500 feet
2,000 feet
3,000 feet
6,000 feet
9,000 feet
12,000 feet
18,000 feet
24,000 feet

High Level

45,000 feet
53,000 feet

18,000 feet
24,000 feet
30,000 feet
34,000 feet
39,000 feet

All levels through 12,000 feet are true altitude (MSL). The levels 18,000 feet and above are pressure altitude. Wind direction is from true north. No winds are forecast within 1,500 feet of station elevation. Also, no temperatures are forecast for the 3,000 foot level or for any level within 2,500 feet of station elevation. Temperature is in whole degrees Celsius and assumed to be negative above 24,000 feet.

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 2426 2726-09 2826-14 2930-21 2744-32 2751-41 275550 276050 276547

Sample message decoded:

DATA BASED ON 010000Z

Forecast data is based on computer forecasts generated the first day of the month at 0000 UTC.

VALID 010600Z FOR USE 0500-0900Z. TEMPS NEG ABV 24000

The valid time of the forecast is the first 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.

FT 3000 6000 9000 12000 18000 24000 30000 34000 39000

FT indicates the forecast location, the numbers indicate the forecast levels.

MKC 2426 2726-09 2826-14 2930-21 2744-32 2751-41 275550 276050 276547

This example shows data for MKC (Kansas City, MO). The 3,000 foot wind is forecast to be 240 degrees at 26 knots. The 6,000 foot wind is forecast to be 270 degrees at 26 knots and the air temperature is forecast to be -9 degrees Celsius. The 30,000 foot wind is forecast to be 270 degrees at 55 knots with the air temperature forecast to be -50 degrees Celsius.

Wind direction is coded as a number between 51 and 86 (vice 01 to 36) when the wind speed is 100 knots or greater. To derive the actual wind direction, subtract 50 from the first pair of numbers. To derive wind speed, add 100 to the second pair of numbers. For example, a forecast at 39,000 feet of "731960" shows a wind direction from 230 degrees (73-50=23) with a wind speed of 119 knots (100+19=119). Above 24,000 feet the temperature is assumed to be negative, therefore the third pair of numbers indicate a temperature of minus 60 degrees Celsius.

If the wind speed is forecast to be 200 knots or greater, the wind group is coded as 199 knots. For example, "7799" is decoded as 270 degrees at 199 knots or greater.

Wind direction is coded to the nearest 10 degrees. When the forecast speed is less than 5 knots, the coded group is "9900" and read, "LIGHT AND VARIABLE."

	NOAA's National Weather Service
	Aviation Weather Center