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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4.0 Comparison with other Buffalo Creek storms in 1996

HMS has prepared a comparison of the key rainfall and weather features
of several other important storms which crossed the Buffalo Creek basin during
1996. An Excel 7.0 spreadsheet workbook has been completed for each of
these storms which includes observed radar reflectivity and associated rainfall
for each observation period, This information has been included on 1.44" disk
with the report, Other readers can obtain a copy of this data by written request
to the author,

The June 12, 1996 storm (Figure 10) was related to a weak cool front
which pushed into northeast Colorado during the early morning hours, Weak
easterly flow developed behind the front creating moisture and wind '
convergence into the foothills of Jefferson County which helped to initiate strong
to, possibly, severe storms.. Two thunderstorms moved over portions of the
Buffalo Creek drainage basin. The first was between 130PM and 245PM and
the second was between 400PM and 515PM, Storm movement was to the
easUnortheast at 10-15 mph, HMS has analyzed the data for the second storm
from 400PM to 500PM but has radar data on order for the first storm which will
be included in the Phase 2 portion of this project.

On August 7, 1996 (Figure 11) a northeast to southwest oriented wind
convergence line developed across western Douglas and southern Jefferson
counties, It is estimated that 20-30 mph southeast winds converged with 10-15
mph northerly winds, creating the convergence line, A weak mid-level
disturbance pushed over northeast Colorado during the middle to late afternoon
hours. One thunderstorm, developing on the convergence line, moved over
portions of the Buffalo Creek basin between 215PM and 315 PM, Storm
movement was to the easUsoutheast at 12-18 mph.

On August 8,1996 (Figure 12) weak easterly low level flow combined
with a 500 mb circulation helped in the initiation of a moderate to strong
thunderstorm that affected portions of the Buffalo Creek drainage basin. The
thunderstorm crossed the basin between 245PM and 350 PM, Storm movement
was to the north at 08-12 mph,

On August 23,1996 (Figure 13) weak easterly low level flow combined
with a 700 mb and 500 mb circulation helped in the initiation of two strong
thunderstorms that affected portions of the Buffalo Creek drainage basin. The
thunderstorms crossed the basin between 255PM and 509 PM, Storm
movement was to the northeast at 04-08 mph.

Finally on September 14,1996 (Figure 14) tropical moisture from ex-
Hurricane Fausto was being pumped into Colorado via southwesterly flow aloft.
It acted in concert with a cut-off low at all levels of the atmosphere to initiate

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