One of the two primary scientific programs in MMM is the Prediction of Precipitating Weather Systems (PPWS) program. Its goal is to advance the understanding and prediction of significant precipitation events in order to substantially reduce forecast errors toward the limits of predictability. The accurate prediction of precipitating weather systems is an important topic in the U. S. Weather Research Program (USWRP). There is good potential for advancements in this area because of emerging operational observing systems, high-resolution non-hydrostatic forecast and data assimilation systems, and the continued rapid growth in computer power. Within MMM, there is broad interest and expertise in the observation, analysis, and prediction of precipitation systems, along with opportunities to leverage division resources through collaboration with other NCAR divisions, government laboratories and the university community. The research within MMM focuses on specific areas where MMM's expertise is best suited to advance the science. These areas include mesoscale dynamics and predictability, the life cycle of mesoscale precipitating weather systems, mesoscale data assimilation and high-resolution numerical weather prediction (NWP). These topics are highly interrelated, and research contributing to the advancement of mesoscale assimilation and forecast systems is focused toward development of a new multi-agency Weather Research and Forecasting (WRF) Model.