9714414 Pfeffer The U.S. Weather Research Program (USWRP) is an interagency activity designed to perform and implement the research necessary to improve the delivery of weather services to the nation. Under this Program, the National Science Foundation, the National Oceanic and Atmospheric Administration, the National Aeronautics and Space Administration and the Office of Naval Research are jointly evaluating and supporting research of high priority to the USWRP. Accurate quantitative forecasting of precipitation (Quantitative Precipitation Forecasting, QPF) has proven to be an especially difficult problem and one where little progress has been made over the last several years. For this reason, better QPF techniques has been identified by both the scientific and operational communities as an area ripe for research. The Principal Investigator will investigate new applications of statistical techniques designed to improve QPF. Two nonlinear methodologies will be pursued in this research with statistics derived from 33 years of 3-hourly surface observations and 12-hourly upper air observations covering the United States east of the Rocky Mountains. One involves the design of neural networks with outputs that correspond to the probability of occurrence of standard precipitation threshold values. The other methodology involves the use of analogs of time sequences (rather than instantaneous values) of synoptic variables obtained from ensemble numerical forecasts to specify precipitation probabilities. ***
