Upper Winds and Temperature Forecast (FD)

FDs forecast wind speed/direction and temperature. Temperatures are not forecast for 3,000 feet and all forecast temperatures for altitudes over 24,000 feet are negative. In addition, the forecast at 3,000 feet is omitted if the terrain elevation is greater than 1,500 feet.

Data for the forecast is taken from upper air sounding measurements of pressure, temperature, relative humidity and wind velocity. Data is sampled at 32 sites twice daily (at 0000Z and 1200Z).