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<br />I <br />I <br /> <br />individual turrets, these clouds did indeed contain supercooled water <br />and significant quantities of ice particles (even some graupel). A <br />number of the turrets also contained significant concentrations of ice <br />nuclei indicating that the ground released ice nuclei was indeed drawn <br />up into the higher levels of convective elements. <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />4.2 Storm of 21-23 March 1978 <br />The second storm studied during the Utah program occurred from 21 to <br />23 March 1978. Figure 4.2.1 contains the surface maps and 500 mb maps <br />for 0500 on 21, 22, and 23 March. On the surface map of 21 March there <br />is an ill-defined low pressure center in California with an accompanying <br />cutoff low pressure center at 500 mb. The temperature in the center of <br />the 500 mb cutoff low was -20oC. During the morning of 22 March a broad <br />low pressure center extended from northern Nevada across Utah and into <br />western Kansas. The upper level cutoff low pressure was moving over the <br />area with light winds from the southwest occurring over the state of <br />Utah at 500 mb. By the next morning (23 March) the low pressure center <br />at the surface had moved into Oklahoma and had consolidated. A broad <br />region of low pressure and ill-defined pressure gradient still persisted <br />across the Rocky Mountains and extended into Utah in association with the <br />upper level low which had moved just east of Utah. Utah was then under <br />light westerly and northwesterly flow ahead of a deep, well-organized <br />system off the west coast. <br />Figure 4.2.2 shows the location and time of each ground generator <br />operated during this storm. Most of the generators were turned on late <br />in the evening on 21 March and continued to operate until noon or evening <br />on 23 March. Eight generators were operated south of the Uinta Range on <br />22 and 23 March, and fou.r were operated west of Fairfield VOR during the <br />afternoon of 22 March. From Figure 4.2.3, it may be seen that 30 to 40 <br />ground generators were operated between 2200 on 21 March to 1300 on <br />23 March. In addition, there was some airborne seeding during the after- <br />noon of 22 March. <br /> <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br />I <br /> <br />41 <br />