Use of Operational 0-6 and 3-9 H Quantitative Precipitation Forecasts for Predicting Heavy Rain Events

摘要

New 0-6 and 3-9 h objective quantitative precipitation forecasts (OBJ) for the coterminous United States have been recently implemented in the National Weather Service. The forecasts are issued in the form of isohyets of both the maximum point precipitation amount and the probability of equalling or exceeding specific amounts in 40 x 40 n mi boxes. After taking into account differences in the event forecast, the performance of the isohyetical maximum amounts were compared with manual and model-generated quantitative precipitation forecasts (QPF's) issued 2-12 hr earlier from the National Meteorological Center (NMC). Results show the accuracy of the OBJ forecasts was substantially better than the longer range NMC QPF's, particularly for the heavier amounts.