Intense extratropical cyclones often impact the West Coast of North America with strong winds and heavy precipitation. The distribution and intensity of precipitation within these storms while they reside over the North Pacific ocean cannot be documented with conventional surface-based measurements. Using combined measurements from several satellite-borne microwave radiometers—the Special Sensor Microwave Imager (SSM/I), the Advanced Microwave Sounding Unit (AMSU-B), and the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI)—we are able to map the distribution and relative intensity of precipitation over the North Pacific with a three hour time resolution. The time period of study coincides with the Improvement of Microphysical Parameterization through Observational Verification Experiment (IMPROVE) field campaigns of January-February 2001 and November-December 2001. In situ aircraft data off the Pacific Northwest coast during the IMPROVE I field campaign is used to validate the satellite derived precipitation. In addition, rainfall distribution from satellite is compared to rainfall prediction from the Pennsylvania State/NCAR mesoscale model version 5 (MM5) operationally run at the University of Washington. Our goal is to support the IMPROVE effort to improve quantitative precipitation forecasting by providing detailed precipitation information over the ocean.