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<br />(NOAA Storm Data). In fact, near the time of the flash flood in southern Jefferson COWlty, major <br /> <br />hail damage and an FO tornado were occurring in the extreme northern portion of Jefferson and <br /> <br />adjacent Boulder counties from a different thunderstorm, <br /> <br />The storm-total rainfall over the Buffalo Creek watershed from the Denver WSR-88D <br /> <br /> <br />radar (FTG) ending at 0800 UTC 13 July as estimated by the PPS algorithm is shown in Figure <br /> <br /> <br />I. The location of the heaviest rainfall associated with the flash flood-producing storm is <br /> <br /> <br />centered very close to the town of Buffalo Creek, located near the outlet of the Buffalo Creek <br /> <br />watershed where it empties into the North Fork of the South Platte River. The terrain in this <br /> <br />region is steep, and the Buffalo Creek drainage basin ranges in altitude from about 6,800 ft MSL <br /> <br />at the outlet up to 11,900 ft. It has an area of 120 km2 and is located at a distance of 75,,93 km <br /> <br />and azimuth of230-237 degrees from the Denver WSR-88D. The forest fire burn area, which is <br /> <br />believed to have played a major role in the severity of the flash flood (see the Appendix), is also <br /> <br />outlined in Fig. 1. <br /> <br />2. WSR-88D reflectivity data <br />Archive Level II radar reflectivity data (Crum et al. 1993) from the Denver WSR-88D for <br /> <br />141 volume scans was ingested into the PPS for the 14 hour period from 1756 UTC 12 July to <br /> <br />0800 UTC 13 July 1996. Thunderstorms first developed in Colorado around 1700 UTe, <br /> <br />however Archive II data prior to 1756 UTC was not consistently available and therefore: could <br /> <br />not be used, <br /> <br /> <br />Over the Buffalo Creek basin the PPS uses reflectivity data exclusively from the: second <br /> <br /> <br />elevation angle (1.5 deg) in constructing the reflectivity hybrid scan and resulting rainfall <br /> <br />4 <br />