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<br />
<br />sizes, Note the similarity of the Rapid City
<br />and Big Thompson flash flood events,
<br />This study describes the meteorological
<br />conditions that produced this localized, ex-
<br />tremely heavy rainfall along the Colorado
<br />Front Range dlll;ng the evening and night
<br />
<br />01'31 July 1976, These conditions are com-
<br />pared with those associated with the Rapid
<br />City, South Dakota, flash flood of 9 June
<br />1972, and a summary of common features is
<br />presented,
<br />
<br />Table 1.
<br />Comparison of maximum measured peak flows during flood events with the drainage areas
<br />involved
<br />
<br />
<br />P.ak Flow
<br />,(ft's.~~~)
<br />
<br />~ qraimlge
<br />Area'"{mF)'
<br />
<br />'~ ~ 'orai~.gb. .
<br />,.A(....
<br />",Imi'l
<br />'it
<br />
<br />~ ~"2~63h
<br />~ 1.';& i:t
<br />'"
<br />
<br />w
<br />
<br />SI
<br />
<br />Ii'
<br />~j
<br />~
<br />'"
<br />
<br />
<br />:tit,;
<br />
<br />'0;'
<br />
<br />
<br />'6;522
<br />,
<br />Ni
<br />
<br />'3,319
<br />l]\ $i;
<br />,1$
<br />
<br />~Many of the data are from Williams (1976).
<br />
<br />2. Meteorological
<br />Conditions Prior to
<br />Storm Development
<br />
<br />A series of upper-air analyses was
<br />Ilsed, in conjunction with hourly surface
<br />analyses, upper-air soundings, radar scope
<br />and satellite photographs, and stability
<br />charts, to study the evolution of
<br />meteoroloi-,,'ical conditions that culminated
<br />in the development of the Big Thompson
<br />storm,
<br />
<br />4
<br />
<br />.LQcati:on~'
<br />!!!i ..~ III ~
<br />
<br />j~
<br />
<br />
<br />8,767
<br />
<br />Little PinWGreek
<br />.. -. ...."" ,",1' /*"8
<br />tributary, f:Jewca~Ue, Utali
<br />
<br />7,210
<br /><
<br />
<br />Dark Gulch', GlewComfort,' Qf! ~
<br />.. ......... em ,....*,"V'" ....... ,..... ......... ..
<br />~olo" dU,;!ng BigiT.hom~so!lJloqd
<br />-C1I" .--,
<br />~
<br />
<br />l
<br />
<br />'Ik
<br />
<br />'\..
<br />
<br />Trujiilb Arr.oyif.near+
<br />!iifl~bo'rG~N ,Me~:\i
<br />
<br />~
<br />
<br />i': ..
<br />Eillorada. CanysOn, Ne~,
<br />
<br />1M
<br />
<br />~
<br />
<br />'520
<br />
<br />~:
<br />Big"'TliompsPrl River .~
<br />mouth at canyon
<br />
<br />
<br />Rapid Creek.at Rapid
<br />CltY,,~S,Dak, ~ .
<br />
<br />ilJ
<br />"
<br />
<br />!II
<br />
<br />\!i
<br />.556
<br />
<br />~A
<br />Ii
<br />
<br />c:u
<br />r,
<br />
<br />36
<br />
<br />"'ljriima's,J\iver. near
<br />'Durango" Cola $
<br />
<br />,y
<br />
<br />ill
<br />
<br />2.1 Synoptic Scale Analyses for
<br />1200 GMT, 31 July 1976
<br />
<br />Detailed surface and upper-air
<br />analyses for 700, 500, and 300 mh are pre-
<br />sented in Figs, 4 through 7, Important sur-
<br />face features included a strong polar high
<br />pressure area centered over southern
<br />Canada, and a weak low pressure area lo-
<br />cated near Grand Junction ill western Col-
<br />orado, A douhle frontal structure at the
<br />periphery of the polar air mass (Fig. 4)
<br />
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