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<br />High Elevation Extreme Local Storms In Colorado-
<br />Implications For High Elevation Site Specific PMP: Update 2000
<br />
<br />John F. Henz
<br />Certified Consulting Meteorologist
<br />
<br />J/fl.jIfP'f
<br />
<br />HDR Engineering, Inc
<br />Hydro-Meteorological Services
<br />Denver, Colorado 802103
<br />jhenz@hdrinc.com
<br />
<br />1. INTRODUCTION
<br />
<br />During the summer of 1996 Henz Meteorological Services (HMS), in support of the Colorado
<br />Climate Center's Extreme Precipitation Study, evaluated the characteristics of historic extreme
<br />precipitation events that occurred over the higher elevations of Colorado and southern Wyoming.
<br />The data sample included flash flooding events selected by the State Extreme Precipitation
<br />Committee and those identified as having special interest to the group. The events evaluated in
<br />1996 are presented below:
<br />
<br />. Event 1: Plum Creek and Kiowa Creek, Colorado; June 16-17, 1965,
<br />. Event 2: Big Thompson Canyon, Colorado; July 31, 1976,
<br />. Event 3: Poudre River and Rist Canyon, Colorado; August 1, 1976,
<br />. Event 4: Frijole Creek, Colorado; July 3, 1981,
<br />. Event 5: Cheyenne, Wyoming; August 1,1985,
<br />. Event 6: Opal, Wyoming; August 16,1990,
<br />. Event 7: Muddy Creek, Colorado; June 20, 1994,
<br />. Event 8: Robideau Creek, Colorado; August 10,1993, and
<br />. Event 9: Pagosa Springs, Colorado; August 22, 1995
<br />. Event 10: Buffalo Creek Flash Flood of July 12, 1996
<br />. Event 11: Fort Collins, Colorado Flash Flood of July 28,1997
<br />. Event 12: Rifle Creek Flash Flood of May 15, 1991
<br />. Event 13: Owl Creek Pass; August 21,1995
<br />. Event 14: Virginia Creek, CO; September 3,1991.
<br />
<br />Two additional significant mountain flooding events occurred in 1999: the July 25, 1999
<br />Saguache Creek and the July 31,1999 Dallas Creek flash floods. Both of these 1999 flash floods
<br />were re-constructed in detail for a consortium of the Colorado Water Conservation Board, U,S.
<br />GeOlogical Survey and the U,S. Bureau of Reclamation. A detailed atmospheric structure was
<br />developed for each of the 16 storm events. These storms were further stratified by their location
<br />either east or west of the Continental Divide as indicated below:
<br />
<br />East of the Continental Divide Events:
<br />Fort Collins, CO (7-28-97), Cheyenne, WY (8-1-85); Plum Creek, CO (6.16-65); Big Thompson, CO (7-31-
<br />76); RistCanyon/Cache La Poudre, CO (7/31,8/1-76); Virginia Creek, CO (9-3-91); Buffalo Creek, CO (7-
<br />12-96) and Frijole Creek, CO (7-2-81),
<br />
<br />West of the Continental Divide Events:
<br />Dallas Creek (7-31-99); Saguache Creek (7-25-99); Opal. WY (8-12-90); Rifle, CO (5-15-93); Muddy Creek
<br />(6-12-94); Robideau Creek, (8-10-93); Owl Creek Pass (8-21-95); and Pagosa SpMngs (8-22-95).
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