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<br />Mr. George Bomar outlined the responsibilities of the Texas Department of <br />Water Resources for ascertaining the value of cloud seeding technology. <br />He described the physiography and general climatic characteristics of the <br />Edwards Plateau and summarized the work of Dr. Don Haragan of Texas Tech <br />University. Dr. Haragan prepared a precipitation climatology of the Edwards <br />Plateau area. This area is characterized by maximum precipitation in May and <br />September and minimum precipitation in winter and early spring. The spatial <br />distribution of average annual precipitation shows an east-west bulge which <br />is probably related to the abrupt rise in elevation along the Balcones <br />Escarpment. Maps of mean monthly precipitation show evidence of topographic <br />influences on several scales ranging from extremely localized to broad.scale <br />features along the escarpment. During the warm season. rainfall occurs as <br />scattered showers or thunderstorms characteristic of localized convection. <br />Heavy precipitation 1n late summer and early fall is due to tropical activity <br />moving west and north from the Gulf of Mexico. These storms are well defi~ed <br />and may result in heavy precipitation over only a portion of the area. <br />Integration of the rainfall from all storms results in the mean precipitation <br />being heavy during September. Winter precipitation is light and results <br />primarily from the overrunning of tropical air. <br /> <br />Professor Walter K. Henry of Texas A&M University described his study of the <br />upper-air climatology of the Edwards Plateau. The purpose of the study was <br />to identify and quantify the upper-air meteorological variables associated <br />with rainfall over the southeastern portion of the Edwards Plateau. Using <br />rawinsonde data from Del Rio, Stephenville, and Victoria for the 6 summer <br />months of 1973 to 1980. 18 parameters were computed for each observation <br />period. These values were compared with the daily rainfall as reported by <br />approximately 80 rainfall stations within the triangle formed by the rawfnsonde <br />stations. Regression equations were formulated relating the 18 parameters to <br />the average areal rainfall amount and to the average areal rainfall coverage. <br />These equations did not have good confidence scores. A method was developed <br />to forecast the days when no seedable rain will occur (about 50 percent of <br /> <br />11 <br />