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<br />00347B <br /> <br />TABLE 5 <br />Percent of long-term maximum spring snowcourse water content for <br />mountainous sub-regions of Colorado in 1977 and 1981. <br /> <br /> Sub-reqion <br />Spring South North East Central West Central Combined <br />1977 35 52 52 48 46 <br />1981 47 61 59 46 56 <br /> <br />Percentages for the two extremely dry winters for each sub-region are <br />somewhat lower than the lowest reported during 1961-74 and particularly <br />low in the south in 1977 (35 percent). The lack of very dry winters <br />during the study period precludes drawing definitive conclusions regarding <br />opportunity for seeding during drought periods. <br /> <br />What constitutes a dry or wet winter in each sub-region during the <br />study period is difficult to determine. We decided to consider winters <br />with water content less than or equal to 80 percent of the long-term <br />average as dry and those with water content greater than or equal to 120 <br />percent of the long-term average as wet. Winters with water content <br />between 80 and 120 percent of the long-term average were considered <br />nonnal. Many other criteria are possible; these criteria were chosen <br />partly because they allowed classification of two to four of the 13 <br />winters in each sub-region as dry and wet. <br /> <br />Identifying Storms <br /> <br />Storms were identified from interpolated border point SOundings. <br />First, the sounding that best represented the air mass about to enter the <br />state was determined. The average 700 millibar (mb) wind direction for <br />the 10 border point soundings was computed and. a sounding chosen whose <br />wind direction to the center of the mountainous area of the state was <br /> <br />17 <br />