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<br />20 <br /> <br />Therefore, summer estimates accurate to within + 3 inches can be made <br />with considerable confidence. <br />Final estimates of average annual precipitation were then generated <br />by simply summing the two seasonal estimates. The results for 151 snow <br />courses are shown in the appendix. The method for deriving these values <br />may be somewhat crude and subjective, but based on familiarity with <br />Colorado precipitation characteristics we are confident that the results <br />are both reasonabl e and consi stent. If error was made, it was made on <br />the conservativesi de--underestimati ng actual preci pitati on. <br />D, Research data sets <br />Data from several major research activities were examined for <br />possible use in this mapping project. For example, precipitation <br />measurements taken in support of the Climax weather modification <br />experiment (Grant, 1984), project Skywater (U.S. Bureau of Reclamation, <br />1976) in the San Juan Mountains, and the Little South hydrology studies <br />on the Poudre River (Meiman and Leavesly, 1974) were examined. Data <br />from these and other similar projects were not used directly in the <br />final analysis. However, precipitation gradients suggested by these <br />higher density mountain networks were examined to improve the subjective <br />"feel" for precipitation patterns in the mountains. These data sets <br />would have been used more rigorously were it not for the excellent <br />accuracy of the original 1931-1960 precipitation analysis. <br />E. Orographic precipitation model results <br />A simple operationally-oriented orographic precipitation model was <br />developed for western Colorado (Rhea, 1978) to diagnose the effect of <br />topography on winter precipitation. The goal was to develop a tool for <br />objectively predicting 12-hour snowfall amounts to aid in avalanche <br />