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<br />22 <br /> <br />V. Resul ts <br />A. Mapping procedure <br />Annual precipitation values were plotted on a mYlar overlay over <br />the original 1931-1960 isohyetal map. A color coding scheme was used to <br />easily identify the priority ranking of each station. During this first <br />mapping step priority 1, 2 and 3 data were plotted. The map was then <br />systematically examined, and all locations were identified where new <br />data points were in conflict with the original analysis, Reconstruction <br />of the isohyets was then be9un using the guidelines shown in Table 1 <br />changing the map to conform to the 1951-1980 data. Where there was no <br />new data and where no other new information was available, the original <br />isohyets were assumed to be correct. <br />The contour intervals used on the original map were retained: <br />1 inch up to 8.00 inches, 2 inches 8.00 to 12.00 inches, 4 inches 12.00 <br />to 20.00 inches, 5 inches 20.00 to 30.00 inches and 10 inches where <br />annual precipitation exceeds 30.00 inches. These interval s were <br />consistent with data density and with the magnitude of precipitation <br />gradients. <br />After this first contouring step, estimates of average annual <br />precipitation based on snow course measurements were added to the <br />overlay. Isohyets were adjusted in the high elevation areas only where <br />2 or more data points were in conflict with the analysis. <br />The final step involved general verification of the analysis based <br />on other information sources such as priority 5 stations, the Rhea <br />orographic precipitation model, research data sets and analyses, and the <br />expert knowledge of individuals very familiar with the hydrometeorology <br />of Colorado, The Colorado Hydrometeorological Committee provided group <br />