FTFIND

This program is designed to measure the meteorological accuracy of terminal forecast (FT) ceiling and visibility elements issued by NWS field offices. Meteorological accuracy refers to the difference between forecast elements and observed conditions, not to FT update (amendment) criteria. The application employs a computationaly simple algorithm to verify whether an observation was within an acceptable range centered on the forecast value. For example, a forecast ceiling of 2100 feet may need to be updated when the observed ceiling is 1900 feet, but meteorologically, the forecast would be considered accurate. Unlike AFOS era verification, which samples and evaluates prevailing FT forecasts only four times per FT (at 3 hrs, 6 hrs, 9 hrs, and 15 hrs), this program evaluates the FT over its entire period, including conditional forecasts (OCNL and CHC). It can evaluate the forecaster's choice of change groups, i.e., times when the forecast elements change. The program also computes difficulty factors in terms of how low and how variable observed conditions are for each forecast.