Recently, NOAA's National Climatic Data Center (NCDC) reprocessed 10 years historical Hydrometeorological Automated Data System (HADS) precipitation data. The reprocessing (from the original format HADS precipitation data) provided an improved product compared to the real-time product in three areas: (1) less missing observations, (2) better assignment of top-hour observations, (3) and improved monthly total precipitation amount. Preliminary results of warm season (April – September) for 3 years (2003 – 2005) in the North and South Carolina domain produced an average 0.25 inches of rainfall when compared to the real-time hourly precipitation product archived at UCAR. The improvement is ascribed to the use of sub-hourly observations as short as 15 min, and accumulated precipitation data from which any decrease in time (either random or gross error) is constrained to be non-negative. We are analyzing spatial/temporal variations of heavy rainfall events (greater than 1.0 inch/hour) from the reprocessed HADS hourly precipitation for 10 years in the Continental U.S.