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<br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />A post-evaluation of rainfall reports associated with <br />the Pawnee Creek flood of July 29-30,1997 in <br />eastern Weld and western Logan counties <br />in northeast Colorado <br /> <br />Executive Summary <br /> <br />An extreme flash flood occurred on Pawnee Creek in northeastern Colorado July 29-30, <br />1997 following several hours of intense rainfall. A survey of the storm conducted a few <br />days afterwards, and published in draft form in October 1997, revealed that extreme <br />rainfall occurred over a fairly large area of eastern Weld County and western Logan <br />County. Storm totals from this preliminary analysis reached 15 inches at the center of the <br />storm, making this one of only a handful of such extreme events ever documented in <br />Colorado history. <br /> <br />Because of the excessive rainfall totals and extreme flash flooding associated with this <br />storm, the Colorado Climate Center at Colorado State University was enlisted to evaluate <br />and confirm the rainfall reports. This report contains and summarizes the results of many <br />interviews with residents of the area that witnessed and, in some cases, measured the <br />rainfall. <br /> <br />The results of this survey conducted one year after the storm confirmed that an extreme <br />event had indeed occurred and that significant rain had already fallen in the previous days. <br /> <br />. From July 19 to 25, moderate to locally heavy rains (generally one to three inches) fell <br />over eastern Weld County bringing beneficial moisture after several weeks of hot and <br />dry weather. <br /> <br />. A widespread heavy rainfall event took place during the evening of July 28 dropping <br />one to two inches of rain over most of eastern Weld and western Morgan counties, <br />enough to produce runotfin many of the noimally-dry creek beds. Locally, as much <br />as three inches of rain fell north of New Raymer. <br /> <br />. On July 29, 1997, heavy rains began in extreme northeastern Weld County during the <br />afternoon. Then around 7:30 PM MDT, very heavy rains began north of Stoneham <br />near the Weld-Logan county line. These heavy rains spread slowly northeastward but <br />also developed and propagated southwestward with the heaviest and most widespread <br />rains falling from approximately 9:00 PM to just after midnight, with lighter rains <br />continuing until 02:00 to 03:00 AM on July 30. No hail was reported with this storm, <br /> <br />11 <br />