Plain English Meaning
A forecast that tells pilots what the wind and air temperature will be at different heights above the ground, so they can plan their flight before takeoff.
Full Definition
A computer-prepared aviation weather forecast that provides predicted wind direction, wind speed, and air temperature at specified altitudes for selected locations across the country, valid for stated time periods. Wind direction is given as the true direction (degrees true) from which the wind is blowing, wind speed is in knots, and temperature is in degrees Celsius. Forecasts are typically issued for altitudes such as 3,000, 6,000, 9,000, 12,000, 18,000, 24,000, 30,000, 34,000, and 39,000 feet. Wind data is omitted for levels within 1,500 feet of the station's elevation, and temperatures are omitted for the 3,000-foot and for any level within 2,500 feet of the .