FLOOD07696

• County: Prowers
• County: Bent
• County: Otero
• Community: Southeastern Colorado
• Stream Name: Arkansas River
• Basin: Arkansas
• Title: The Arkansas River Flood of June 3-5, 1921
• Date: 1/1/2022
• Prepared For: State of Colorado
• Prepared By: USDOI
• Floodplain - Doc Type: Flood Documentation Report

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12

THE ARKANSAS RIVEn FLOOD OF JUNE 3-5, 1921.

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province of Albertn on June 1. By the 2d it hnd displnced n low-
pressure area over the upper Missouri Valley, and on the 3d it was
over Manitoba and the northern part .of North Dakotn. Between
the 3d and 4th the movement was very slow, and it advnneed only as
far as northeastern Minnesota. By June 5 the area had reached It
point over the Great Lakes. During this period an area of low pres-
sure (29.7 inches) had developed over westE~rn Arizona and remained
over the southern Rocky Mountain plateau for several days. The
difference in pressure between the" high" and" low", areas caused
air currents to travel from thEI "high" to the" low" in an endeavor
t~ equalize the pressure. The movement from the" high" area was '
ohtward and downward in a general clockwise direction toward the
"ilow" area. '
The relative positions of the ureas of high amI low pressure caused
the storm to come primarily :Erom the east or northeast. All along
the front range in Colorado mnd New Mexico hea.vy mins occurred
when the clouds were forced upward by reaching the mountains, but
nowhere else was the rainfall as heavy as in the upper Arkansas'
Valley.
The general line of the front range and foothills bears to the south.
east from the 'Wyoming boundary to Pikes Peak, a semidetached
mountain mass rising abruptly from the plaiins. South of Pikes Peak
the front range and line of foothills turn sharply westward for 20
miles and then near Canon City &'wing quickly to the south and south.
east and keep that course for 20 miles. This reentrant angle in the
generalline<<?f the front, rang(1 had a marked influence on the storm,
,~a1!sing it to concentrate at that point. From the statements of ob.
.'servers it is evident that the storm was deflected by Pikes Peak and
,;dame into the smaller area of. heavy precipitation (PI'. 15-16) from
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.j ,the north. Owing to the funnel shape of thl~ valley opening upon the
'(P"ll!ins, air rushed into it both from, the northeast and from the south.
,,'.;'a51:. around the end of Greenhorn Mountain. The rushing together
gaV'e the combined air currents II more or less circular movement that
callsed them to swing around to the north and northwest, where they
met the storm coming down from the north. This circular motion
caused the clouds to impinge against the side of the mountains so
'l'iolently that they rose quickly and precipita.ted their moisture with
great rapidity. Thunderstorms and hail, which occui-red at the be-
'ginning of the rain, indicated the strong convective chamcter of the
storm.
,'. The Weather Bureau received reports of precipitation at a nuinb~r
of points in this general region, which are summarized in the folio)\'.
ing table: ,'. "

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