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considered further for local storm transposition relative to the local storm PMP calculation. The key general storms selected for evaluation are listed below in Table:;:, Two forms of general storms were apparent: one with enhanced orographic precipitation and little or no embedded thunderstorm activity, such as the Big Elk Meadow storm, and another with little orographic predpitation but considerable widespread thunderstorm activity, such as the Plum Creek Floods of June 1965. Table 2: Listing of historic general rain storms affecting Mason Reservoir, CO PMP, Detailed meteorological data was obtained fOI" storms whose names are shaded. Stonn Name Penrose, CO Flood Cher Creek, CO Gibson Dam,Montana Plum Creek, CO Big Elk Meadow, CO 1969 Bi Thorn son, CO * Fri"oJe Creek, CO Date June 3-5,1921-_. Ma 30-31,1935 June 6-8 1964 June 15-17,19155 May 4-8,1969 Amount of rain 8 -13 inches 124 hours 22 inches I 6 hours 16.2 inchl~s 136 hours 15-25 inches I 7'2 hours 15-20 inches 17'2 hours .- -, 6 12-15 inches 16, hours 12-15 inches 16, hours Jul 31 - Aug~~;t '!L197 Jul 2-3,1981___"__ Little quantitative information is available on the Penrose, Colorado floods of June 3-5,1921, HMS has performed a detailed historical storm analysis which indicates that the Penrose storm was actually two separate storm events rather than one, The first storm event occurred on the afternoon and evening of June 3, 1921 and affected mainly the northern portions of the Arkansas River drainage areas north of Penrose with estimated rainfall of 8 to 11 inches in 6 hours or less, This strong thunderstorm system formed in the southern foothills of Pikes Peak on the afternoon of June 3 and moved southwestward and then south into complex terrain. A second storm event formed over the foothills southwest of Pueblo over southern portions of the Arkansas River drainage centered near Boggs Flat on the afternoon and evening of the same day, This storm system was stronger than the first and produced 8 to 13 inches of rain in less thaI' 6 hours with runoff causing severe flooding in Pueblo. These two storm events appear similar to the June 1965 Plum Creek events due to their close occurrence within a four day period and predominance of thunderstorm activity, The Cherry Creek 1935 event occurred over the non.hern face of the Palmer Divide at an elevation of 6.900 feet. This storm produced about 22 inches of rain in 6 hours or less. Figure 2.11 in HMR 55A clearly shows the rainfall axis extends from southwest to northeast sugge'sting that winds aloft W4~re southwesterly above mountain top level. Discussion of the storms in HMR 6