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l. Introduction The performance of the WSR-88D Precipitation Processing System(pPS) (Fulton et al. 1998) is examined for a flash flood event that occurred in the evening of 12 July 1996 in the small rural to\\TI of Buffalo Creek. Colorado located about 50 kIn southwest of Denver in mountainous southern Jefferson County. Two drownings and extensive property damage occurred in the town and the immediate vicinity associated with the rapid rise of the Buffalo Creek that flows through town. In the Appendix is a memorandum written by the National Weather Service (NWS) Forecast Office in Denver describing the impacts of the flood event. Brandes (1997) describes a preliminary study of the Buffalo Creek event that compares rainfall estimates from the WSR-88D and S-Pol dual polarization radars. Thunderstorms first developed in central Colorado around II a.m. MDT 12 July (1700 UTC) and moved generally southeastward. The most intense rainfall over the Buffalo Creek watershed occurred primarily between 8 and 9 p.m. MDT 12 July (0200 and 0300 UTC 13 July). At that time a weak surface low in Utah was producing southeasterly surface winds in eastern Colorado that were advecting high dewpoints in the low to mid 60's F along the front range of the Rocky Mountains. A weak stationary front was draped northwest-to-southeast across the state, and an upper-level ridge over the West coast produced mid and upper-level west- northwesterly winds of 30-40 knots over Colorado. The atmosphere was convectively unstable with a Lifted Index of -4 from the 00 UTC 13 July Denver sounding. There were some unofficial reports of hail associated with the flood-producing storm. There were II official hail reports ranging from 0.75-1.75 inches in diameter and three FO tornadoes throughout the same day associated with other severe thunderstorms in Colorado 3