1. Time and date:
DATA BASED ON 010000Z
Forecast data is based on computer forecasts generated the first day of the month (01) at 0000 UTC (Coordinated Universal Time), referred to as "zulu."
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. You can shift time covered by the chart to 1200 hour (12 noon) and 2400 hour (midnight) by clicking one of the buttons in the upper right hand corner.
2. Wind speed and direction:
|
FT
|
3000
|
6000
|
9000
|
12000
|
18000
|
24000
|
30000
|
340000
|
390000
|
|
BOS
|
2426
|
2726-09
|
2826-14
|
2930-21
|
2744-32
|
2751-41
|
275550
|
276050
|
276547
|
This example shows data for Boston. The wind at 3,000 feet is forecast to be 240 degrees at 26 knots. The wind at 6,000 feet is forecast to be 270 degrees at 26 knots and the air temperature is forecast to be
-9 degrees Celsius. The wind at 30,000 feet wind is forecast to be 270 degrees at 55 knots with the air temperature forecast to be -50 degrees Celsius. Wind direction is coded to the nearest 10 degrees.
Under 100 knots: Wind direction is coded as a number between 00 and 36. Wind speed is coded as a number between 00 and 99.
Over 100 knots: Wind direction is coded as a number between 51 and 86. To derive wind direction subtract 50 from coded wind direction. 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, "779980" is decoded as 270 degrees at 199 knots or greater, with a temperature of -80 Celcius..
NOTE: all wind speeds are in knots and altitudes through 12,000 feet are MSL. Above 18,000 feet altitudes are pressure altitudes. Wind directions are from true North. No temperatures are forecast for the 3,000 foot level. Temperatures are in degree's Celsius.
3. Conversion ratios and sites:
One knot = 1.15 miles per hour (1.150777945 exactly). 30 knots = 34.5 miles per hour. Here is a converter: click here
Celsius to Fahrenheit: -9 degrees Celsius = 15.8 degrees Fahrenheit; -14 degrees Celsius = 6.8 degrees Fahrenheit; -21 degrees Celsius = -5.8 degrees Fahrenheit; - 32 Celsius = -25.6 degrees Fahrenheit; -41 degrees Celsius = -41.8 degrees Fahrenheit; -50 degrees Celsius = -58 degrees Fahrenheit. Here is a converter: click here.
Meters to feet: One meter = 3.2808399 feet. Here is a converter: click here.
