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reporting only 6% of average. The North Platte Basin was the highest, but still only 44% <br />of average. With the shallow snowpack accumulations and early spring -like <br />temperatures, many sites had completely melted by May 1. Meltout at most sites across <br />the state progressed six to eight weeks earlier than normal. <br />Figure 11.1. April Snowpack in Colorado <br />APRIL 1 SNOWPACK COLORADO STATEWIDE <br />190 <br />148 <br />198 <br />97 <br />Ion <br />05 <br />} <br />O SC <br />C <br />9} <br />U <br />� 9D <br />a <br />40 <br />EE <br />Year <br />Unusually warm and dry weather allowed snowmelt to proceed unabated throughout the <br />month of May. This left the state with a snowpack of only 2% of average and 10% of <br />2001 totals on this date. Only the Yampa and White, and North and South Platte basins <br />had any snowpack remaining. As a percent of average, they ranged from 15% in the <br />North Platte Basin, to only I% in the South Platte Basin. By and large, the state's basins <br />had melted out about two months earlier than normal. In many parts of the state this <br />meager snowpack was sitting on very dry soils. As melting began, much of this moisture <br />simply soaked into the ground, never making it to the streams. In addition, windy <br />conditions and low humidity during much of May led to direct sublimation (vaporization <br />of snow surface) of the snow and substantial losses of water. <br />Average statewide precipitation data for the period from October 2000 to September <br />2002 (Figure II.2) illustrate why runoff this year was so low and also suggest why water <br />managers were, to some extent, caught off guard. Spring precipitation was well below <br />0 <br />68 69 70 71 73 73 7o, 75 76 77 78 79 80 Si 82 83 8. 85 86 87 88 89 90 91 92 93 9. 95 96 97 93 99 00 01 02 <br />