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<br />SEP-29-97 MaN 03:34 PM TRC NORTH AMERICAN WX <br /> <br />FAX NO. 801 972 3813 <br /> <br />p, 08 <br /> <br />Questions <br />4, 5, and 11: <br /> <br />Question 6: <br /> <br />(,ldngIJlOnuil.wpd <br /> <br />Certain storm characteristics will be monitored to determine whether a <br />storm, or 11 portion of a storm, is to he seeded. Criteria that will he <br />considered will include cloud top temperature, lower-level atmospheric <br />stability, height of cloud base, and aJnnass temperature. General <br />seeding guidelines will call for seeding if the cloud top temperatures are <br />expected to be from -10.C to -30.C, there are no low-level stable <br />atmospheric layers which would restrict the vertical dispersion of the <br />seeding material, cloud base heights that are below the crest of the <br />mountains which comprise the intended target area, and lower-level <br />temperatures which are cold enough to promote silver iodide nucleation <br />(-S.C or colder) to which the silver iodide material can reasonably be <br />expected to travel. <br /> <br />The intended target area serves as an important winter snowpad. <br />accumulation area. As the snowpack melts during the spl'ing and <br />summer months, it provides surface runoff and underground water <br />recharge. 'Chis water is utilized by a number of different water users <br />through streamflow diversions, storage in reservoirs and subsequent <br />dispensing to water users, and recharging of groundwater. The <br />objective of the proposed operation is to increase the availability of <br />these natural water supplies originating in the target area. The <br />anticipated level of enhancement of the naturally occurring <br />precipitation in the target area during the period of operation is on the <br />order of 10 to 15 percent increase in precipitation. The enhancement in <br />surface streamflow is expected to be in the same range as the increa.se <br />in precipitation. <br /> <br />Increases in precipitation in the target area would provide additional <br />water supplies to the resident flora. 'Supplemental streamflow should <br />provide an enhanced environment for the resident fish populations. <br /> <br />The program should improve recreational opportunities in the target <br />area, increase agricultural production, and provide additional water <br />supplies to municipalities. <br /> <br />Research at Colorado State University has indicated that minute <br />particles of silver iodide have the ability to convert cloud water <br />droplets below approximately .S.C (supercooled) into ice crystals <br />(Garvey, 1974). Other research in numerous mountainous loc.'ltions in <br />wintertime has indicated that supercooled water droplets occur in <br />storms that affect such areas (Super and Boe, 1988) (Solak, et a\., <br />1988). Specifically, research conducted over the Grand Mesa in <br />western Colorado (Thompson and Super, 1987) has indicated that <br />periods with supercooled clouds occur during winter storms. Ludlum <br /> <br />2 <br />