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<br />proceeding toward Denver. Flood waters spread 10 1/2 mile or more in width and <br />destroyed homes, trailer courts, businesses or anything in its path causing <br />damages estimated as high as $250 million or more in Metropolitan Denver. The <br />flood waters passed on through Denver to add to the already flooded South Platte <br />River through Fort Morgan, Sterling, and Julesburg on into Nebraska. One man <br />was drowned in the flood waters near Larkspur. <br /> <br />"On June 17th heavy rain with some !''' hail battered an area from Fountain nOlth <br />through the Colorado Springs area to Peyton, northeast of Colorado Springs. <br />Roads, bridges, and crops were heavily damaged. The towns of Peyton, Ellicott, <br />Rush, Calhan, Ramah, and others were isolated for a time by flood waters." <br /> <br />HMS has compiled detailed atmospheric structure information for this event which was a <br />General Convective Storm (GCS). This was done using data from the HMS Sform <br />Archives, the National Climate Data Center, and the Colorado Climate Center. The <br />sounding processing program, RAOB Version 3.5, was w;ed to compute a representative, <br />objective sounding for this event. <br /> <br />An analysis of the rainfall patterns associated with this event has been completed. This <br />analysis showed that the Plum Creek storms were dominated by the occurrence of <br />thunderstorm rainfall which fell over a 6- to 72- hour period. Traditional PMI' general <br />storm criteria consider a 72-hour storm period. The Plum Creek floods OCCUlTed over a <br />large area of the eastern Colorado plains for a period ofn hours. In general, rainfall <br />did not occnr throughout the entire 72 hours OVl~r an individual basin but focused <br />on discrete 3 to 12 hour periods at anyone place. <br /> <br />Figure 5 shows that the rainfall on June 16th fell along a rougbly north-south axis which <br />parallels but largely avoids the Front Range foothiHs in EI Paso, Douglas, and Arapahoe <br />Counties. This rainfall axis is paralle] to the mean cloud layer winds which were blowing <br />from 190 degrees. The heaviest rainfall occurred from Palmer Lake to Larkspur to <br />Cherry Creek Reservoir. Note that pockets of rainfall suggest that stronger stonn cells <br />existed along the rainfall axis. This pattern is suggestive of train-echo rainfal.l effects <br />in which cells repeatedly formed off Palmer Ridl~e and tracked along a <br />meteorologically preferred path. <br /> <br />Contrast the roughly north-south rainfall axis ofJune 16th to the rainfall axis of June 17th <br />which runs roughly southwest to northeast (Figure 6). On this date the rainfall axis runs <br />from Fountain to Calhan to Agate or about 45 degrees to the right of the June] 6th <br />rainfall axis. Cloud layer winds on June 17th were blowing from 210 degrees which <br />shifted the rainfall on June 17th to the east of the preceding day's rain axis. Again, the <br />location and intensity of rainfall cells suggests that train-echo rainfall was produced <br />by the thunderstorms repeatedly forming on the south,ern foothills of the Pikes Peak <br />orographic enhancement area. <br /> <br />Please note that the rainfall patterns of June: 16th and 17th did not overlap any <br />basin ou both days. Additionally, no general rainfall from non-thunderstornl sources <br /> <br />10 <br />