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<br />55A indicates a strong low level jet and moist tongue were present and moved <br />from west to east, possibly along a stationary or warm front which extended from <br />east-central Colorado into Kansas. These fa(:tors are not favorable for <br />storms to remain stationary along the Colorado mountains and foothills so <br />transpositioning of this storm was not considemd further, <br /> <br />The general storms included two, mainly orographic events, with no recorded <br />thunderstorm activity: the Big Elk Meadow event of '1969 and the Broomfield <br />1973 storm. These spring storms includecl significant amounts of snowfall at <br />elevations above 10,000 feet in the basins, For transposition to the Mason <br />Reservoir basin these storms would have produced snowfall with little or no <br />rainfall without seasonal adjustments. Thus, these storms were adjusted two <br />weeks into the warm season period for tmnsposition considerations, <br /> <br />The heaviest historic general storm rclinfalls were observed on a series of <br />thunderstorm event days which occurred with little 01' no orographic rainfall, The <br />Plum Creek 1965, the Big Thompson Cianyon 197'6, and the Frijole Cmek <br />1981 storms all occurred with similar meteorological structun~s, Each of <br />these storms occurred when strong low level winds 'forced orographic lift of low <br />level moisture off the plains into the higher topography of the Front Range <br />foothills. <br /> <br />The Frijole Creek storm is similar in meteorological structure and floodin~J <br />magnitude to the Big Thompson Canyon storm, Over 14 inches of rainfall was <br />produced in less than 3 hours over the Frijole Creek basin just south of Trinidad, <br />Colorado during the late evening hours of ,July 2, 19B1, Three people were killed <br />by the flash flood when their coal train was swept into the flood waters by a <br />collapsing bridge over Frijole Creek, This storm has not achieved the notoriety <br />of the Big Thompson Canyon storm becaLls1e of the low loss of life and its <br />occurrence in a low density population area of southern Colorado. However, the <br />storm's meteorology is very similar to that of the Big Thomps1on stenn. <br />HMS has recommended this storm for more detailed review by the Colorado <br />Extreme Precipitation Event Study. The Frijole Crel~k storm is mcommended <br />for transposition to locations soutl1 of Pall mer Divide while thE~ Big <br />Thompson event is recommended for transpositiion to locations north of <br />Palmer Divide. Both storms will be considered in the present study, <br /> <br />While these two storms were very intense, their storm total rainfalls were limited <br />to a 6 hour or less period, As a result these two storms tend to pale when <br />compared to the June 1965 Plum Creek storms which raged for a three clay <br />period along the Palmer Divide producing rainfall centers equaling or exceeding <br />8 inches, The general storm pattern which produced these storms affected a five <br />state area over a seven day period. Clearly the neEld for multipll~ day I~vents <br />in describing the general PMP storm is supported by the climatology. <br /> <br />7 <br />