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18 october-April average precipitation (inches) April 1 average snowpack water content (inches) z = elevation (feet) applicable from 8,000' to 10,300' 2 r = 0.32, with a correlatio.n coefficient (r2) of 0.32 the accuracy of this R = relationship is far from perfect. It does, however, supply a framework for making an objective and reasonable first approximation of winter season precipitation at locations where the elevation and the average April 1 snowpack water content are known. According to this expression, as elevations approach 10,850 feet the ratio approaches 1. This means that April 1 snowpack water content becomes equal to (or greater than for elevations above 10,850 feet) the October-April precipitation. This is not an acceptable conclusion since the April 1 snowpack as defined by its time of observation does not include any of the precipitation that fall s duri ng the month of Apri 1. For thi s reason, the regression relationship was only used for elevations up to 10,300 feet. At higher elevations, where melting during the month of April is often not significant, May 1 average snowpack was used as a direct estimate of October through April average precipitation. May 1 snowpack is logically a slight underestimate of actual precipitation because some melting and sublimation/evaporation occurs during the 7-month winter season. However it is conceivably a better estimate of precipitation than actual gage measurements. This is possible because of inefficient gage catch which often occurs in windy, exposed locations. Part of the reason for the 0.32 correlation coefficient is that factors other than elevation affect the precipitation/snowpack ratio, From the Colorado data it is apparent that factors such as latitude,