FLOOD00419

• County: Jefferson
• County: Park
• Community: Buffalo Creek
• Title: The Buffalo Creek Flash Flood of July 12, 1996 Draft - A Reconstruction of Rainfall and Meteorology
• Date: 7/12/1996
• Prepared For: CWCB
• Prepared By: Henz Meteorological Services
• Floodplain - Doc Type: Flood Mitigation/Flood Warning/Watershed Restoration

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5.0 Conclusions

The town of Buffalo Creek, Colorado was struck by a deadly flash flood
about 900PM on the night of July 12, 1996. The flash flood killed two residents
and produced several hundred thousand dollars of damage to the town. The
cruel irony of the flash flood is that it followed a massive forest fire which burned
12,000 acres of nearby forest land during May 1996

This report presents a coherent presentation of the timing, aerial coverage
and intensity of the rainfall which produced the Buffalo Creek flash flood, Use of
radar data and standard surface and upper air observations was made to
produce precipitation mapping of the rainfall on July 12'h and contrast it to the
rainfall associated with several additional storm events which occurred over the
Buffalo Creek basin during the post-fire period of 1996. Finally, the report
presented information on the meteorological causes of the primary July 12th
flash flood event and contrasted it to the causes of the other lessor events which
occurred.

The Buffalo Creek Flash Flood of July 12, 1996 occurred on one of the
most weather active days of the summer of 1996. Two tornadoes, 11 damaging
hail reports and numerous wind damage reports were logged by the NWS in
Denver, The flash flood producing rainfall occurred simultaneously with severe
weather, tornadoes and hail, in the Denver metro area,

HMS radar records indicated that four storm periods occurred across the
Buffalo Creek watershed on July 12, 1996:

1. Storm Period 1: 210PM until 228PM, a light shower across the lower third
of the basin,

2. Storm Period 2: 612PM until 710PM, rain showers and two moderate
thunderstorms across the western third of the basin.

3. Storm Period 3: 739PM until 913PM, a line of severe thunderstorms cross
and go stationary over the watershed producing the flash flood,

4, Storm Period 4: 918PM unti11023PM, post-flash flood thundershowers and
showers cross the lower half of the watershed.

A severe thunderstorm which formed in central Jefferson County
produced severe weather in central Jefferson, western Arapahoe and northern
Douglas Counties between 655PM and 800PM, More importantly it produced a
gust front boundary of very humid northeasterly winds of 20-30mph which moved
southward into the Buffalo Creek watershed by about 800PM. This gust front
provided the meteorological mechanism which caused the Buffalo Creek

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