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<br />I' <br />I <br />I <br /> <br />Under some conditions rainfall augmentation over large areas <br />can be produced by seeding atop the leading edge of a gust front. <br />Updrafts found there have wide variability---from 100 - 200 feet <br />per minute to 1000 - 1500 feet per minute, or more. Most often, <br />when this particular condition occurs at night and there is no <br />threat of hail developing from new storm growth, seeding to <br />increase rainfall appears highly productive over large areas. <br /> <br />There is one other form of cloud system that appears to have <br />important seeding potential to produce precipitation in Kansas: the <br />multiple celled convective system. This starts as a cluster of <br />small, weak air-mass clouds developing over a relatively small <br />area---typically about 10 - 30 miles in diameter. If one, or more, <br />of the clouds can grow sufficiently to merge with another they tend <br />to continue growing, the added growth allows the merged clouds to <br />continue capturing other nearby smaller clouds thereby increasing <br />in size and intensity. Such systems are capable of eventually <br />producing precipitation over large areas and with cloud seeding <br />they persist ,longer than normal storms. Updrafts initially found <br />within such a cluster of cells are often embedded or difficult to <br />locate, however, once the system grows to sufficient size, updrafts <br />generally organize better and become easier to seed. . This type of <br />system has responded positively to cloud seeding in the past <br />producing abundant rainfall over several hundred square miles, or <br />more, at a time. <br /> <br />I <br />I <br /> <br />Most important research on the dynamics of the multiple celled <br />convecti ve system '/Jas done in Texas. However, earlier' radar <br />studies 1972 - 1974 of Western Kansas clouds done by former KSU <br />Professor and State Climatologist, L. Dean Bark, found Western <br />Kansas a fertile area'for breeding these smaller cell clusters. <br />Comparisons of data seem to suggest Western Kansas may be even <br />better than the area in which the Texas experiment was successfully <br />conducted. Several years ago little attention would have been paid <br />to those weak-appearing multiple-celled cloud clusters until one <br />grew much larger. For the past several years, however, we have <br />watched for these particular targets of opportunity to present <br />themselves and attempted to begin early seeding of the clustered <br />cloud systems in hope of catching the "window of opportunity" to <br />increase rainfall. Spectacular results appear to have occurred on <br />past occasions. <br /> <br />12 <br />