Section 4. Winds and Temperature Aloft Forecast (FD)

9-4-1. GENERAL

Winds and Temperature Aloft Forecasts (FD) are computer-prepared and issued by the NMC at Suitland, Maryland. The forecasts are valid 6 (FD1/8), 12 (FD2/9), and 24 (FD3/10) hours after the observation date/times of 0000Z and 1200Z upon which they are based. An unscheduled amendment to an FD may be prepared and issued by a WSFO.

9-4-2. LEVELS FORECAST

Dependent upon station elevation, FD1/2/3 wind forecasts are issued for the following levels: 3, 6, 9, 12, 18, 24, 30, 34, and 39 thousand foot levels. 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. The minus signs are deleted preceding the temperatures at the 30, 34, and 39 thousand foot levels. FD8/9/10 are for the 45,000 and 53,000 foot levels. They are not normally disseminated on Service A, but are available on request/reply.

9-4-3. SCHEDULES

TBL 9-4-1
Winds/Temperature Aloft Forecast Schedules

9-4-4. DISTRIBUTION

All FDs are transmitted to the WMSC by NMC. Distribution by the WMSC is accomplished in accordance with established program requirements. Amended FD data prepared and entered by a WSFO is distributed to the same users as the original product prepared by NMC.