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<br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br />. <br /> <br />snow water content and precipitation back to above average in portions of the target area. <br />However, the northern and central portions of the Gunnison River Basin received less <br />precipitation. As a consequence, water year precipitation (and in some cases snow water <br />content) remained below average. Then, an unusually warm, dry March resulted in a substantial <br />amount of snowmelt for so early in the season, melting as much as half or more of the snowpack <br />below about the 9,500-ft level. A couple of storms in early April added to the snowpack, <br />although both snow water content and water year precipitation remained below normal as of <br />April 15, the end of the seeded season. Figures 3.1 to 3.3 show snow water content and <br />precipitation, and normals, at three SNOTEL sites for the 2003-2004 winter season. It can be <br />observed from these figures that the precipitation, and in two cases, snowpack water content, <br />increased by 3"-5" during the first two weeks of April. It turned out that the most seeding on any <br />storm during the winter occurred on the April 9-10 storm. <br /> <br />3.1 Operational Procedures <br /> <br />In operational practice, an approaching storm was monitored at the NA WC operations <br />center in Salt Lake City, utilizing online weather information. If the storm met the seedability <br />criteria presented in Table 2-1, and if no seeding curtailments or suspensions were in effect, an <br />appropriate array of seeding generators was ignited and adjusted as conditions required. Seeding <br />continued as long as conditions were favorable and precipitating clouds remained over the target <br />area. In a normal sequence of events, certain generators would be used in the early period of <br />storm passage, some of which might be turned off as the wind direction changed, with other <br />generators then used to target the area in response to the evolving wind pattern. The wind <br />direction during productive storm periods in Gunnison County usually favors a westerly or <br />southwesterly direction, so that the generator sites on the west/southwest side of the target areas <br />were used most often. <br /> <br />12 <br />