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<br />sound physical foundation for the modification hypotheses, their operational <br />implementation, and the;r extension to other areas. The current Project <br />Skywater program includes four major efforts: the High Plains Cooperative <br />Program (HIPLEX), the Sierra Cooperative Pilot Project (SCPP), the Colorado <br />River Basin Project (CRBP), and the Southwest Drought Rain Augmentation <br />Research Program. <br /> <br />1. High Plains Cooperative Program (FY 1980--$5.6 Million) <br /> <br />HIPLEX is a research program to develop a practical, scientifically <br />sound, and socially acceptable technology for precipitation management <br />applicable to summer convective cloud systems over the High Plains region of <br />the United States. It is a joint effort between the WPRS and state and local <br />agencies from the High Plains region. WPRS has responsibility for the <br />meteorological technology development, including hypothesis testing and <br />verification, seeding systems development, and evaluation. The states have <br />accepted primary responsibility for nonmeteorological technology development, <br />including impact assessment, legal and institutional arrangements, and local <br />decision-making criteria. <br /> <br />Major HIPLEX objectives are to identify those conditions for which <br />seeding warm-season convective clouds in a prescribed manner will lead to <br />increases, no effect, or decreases in precipitation and to determine the areal <br />extent and magnitude of those effects. As the scientific uncertainties <br />concerning natural and modified processes are reduced, research will progress <br />from the relatively simple cumulus congestus to more complex and extensive <br />cloud and mesoscale systems. <br /> <br />Three research sites--in Montana, Kansas, and Texas--were selected as <br />representative of the varying cloud characteristics, precipitation mechanisms, <br />and socioeconomic systems along the High Plains. Following 3 years of <br />background studies, a randomized experiment (HIPLEX-l) was initiated in 1979 <br />at the Miles City, Montana, site. This experiment is exploring the hypothesis <br />that both the frequency of occurrence and the amount of rainfall from small <br />cumulus congestus clouds will be increased by seeding with drJ ice for <br />microphysical effects. <br /> <br />The Texas HIPLEX program has included background and exploratory studies <br />on small-to-moderate-sized convective clouds. These studies are a~pected to <br />lead to a randomized- seeding experiment in 1982 or 1983. <br /> <br />Activities at the RIPLEX site in Kansas have been discontinued because <br />analyses and experience show that about two-thirds or the days of interest to <br />HIPLEX (i.e., days with significant convective development) are also days for <br />which severe weather watches or warnings affecting the project area are issued <br />by the National Weather Service. To avoid even the appearance that cloud <br />seeding causes or aggravates severe weather, the ~~RS suspends activitie~ on <br />days with forecasts of tornadoes, severe thunderstorms, hail, strong surface <br />'Ninds, or heavy precipitation. With this restriction, too few a~peri~ental <br />days remained to justify continuing that field effort. However, studies to <br />date have shown that Kansas clouds exhibit characteristics rNhich on some days <br /> <br />- li - <br />