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.' . . . NWS 11 May 2001 I States, Volume III - Colorado, 1973 Format - For each question, this document provides (in the format shown): I. The question as recorded in the minutes of the Technical Meeting. Answer recorded in the minutes of the Technical Meeting. Answer I. The NWS response where required. In those cases where no response is required, the words "No response needed" are used. Questions and Answers 1. Original analysis of the 1935 storm (Cherry Creek and Hale, NWS Hydro 33) cannot be easily challenged with the available data, but there are concerns about the depth and areas associated with that storm and the impact they have on later Colorado PMP assumptions. (Doesken) The group did not reach consensus. The NWS will examine a way to verify this assumption. Answer 1. All of the important storms, as defined in HMR 55A (pages 18-19) for Colorado, were examined. These storms were all east of the Continental Divide with elevations of 6900 feet or less at the center of the storm. The highest storm elevation found was the Cherry Creek storm. The estimated 386 mi2 average depths as a percentage of their 10 mi2 average depths for the relevant storms east of the Continental Divide were determined for durations of 6, 24,48, and 72 hours. The storm rainfall for 72 hours for all storms was 6.3 inches or greater. These data, along with the Gibson Dam, Montana, storm of 1964 are given in Table 1. The data show a wide range of values at the four durations. At 6 hours, the percentage values range from 42% at Loveland, Colorado to 93% at May Valley, At 24 hours, the lowest value is 46% at Cherry Creek and the highest is 98% at May Valley. Similar values are found at 48 and 72 hours. The values found in Colorado are consistent with the values derived for the Cherry Creek Study. The percentages for Plum Creek, just west of Cherry Creek and with similar topography within the basin, are all greater than the values derived in the Study except for the 6-hour duration. 4