THE WSR-88D RAINFALL ALGORITHM

A derailed description of the operational WSR-88D rainfall estimation algorithm is presented. This algorithm, called the Precipitation Proce ssing System, produces radar-derived rainfall products in real time fo r forecasters in support of the National Weather Service's warning and forecast missions. It transforms reflectivity factor measurements int o rainfall accumulations and incorporates rain gauge data to improve t he radar estimates. The products are used as guidance to issue hood wa tches and warnings to the public and as input into numerical hydrologi c and atmospheric models. The processing steps to quality control and compute the rainfall estimates are described, and the current deficien cies and future plans for improvement are discussed.