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<br />702090 (4~1) <br />Bure&u ot Recl&m&Uon <br /> <br />1. REPORT NO. <br /> <br />TECHNICAL REPORT STANDARD TITLE PAGE <br /> <br />r'lIOYE~.ME~~~.CC;aSllON N~. <br /> <br />" "' 3. RECIPIENT'S CATALOG NO. <br /> <br />Evaluation of Operational Ooud Seeding in <br />Western Kansas <br /> <br />5. REPORT DATE <br />November 1987 <br />6. PERFORMING ORGANIZATION CODE <br /> <br />4. TITLE AND SUBTITLE <br /> <br />D-1210 <br /> <br />7. AUTHOR(SI <br /> <br />8. PERFORMING ORGANIZATION <br />REPORT NO. <br /> <br />. <br /> <br />A.S. Dennis, R.L. Eddy, and R.M. Rasmussen <br /> <br />I. PERFORMING ORGANIZATION NAME AND ADDRESS <br />Bureau of Reclamation, E&RC <br />Division of Atmospheric Resowces Research <br />PO Box 25007 <br />Denver CO 80225 <br /> <br />10. WORK UNIT NO. <br /> <br />,1. CONTRACT OR GRANT NO. <br /> <br />13. TYPE OF REPORT AND PERIOD <br />COVERED <br /> <br />12. SPONSORING AGENCY NAME AND ADDRESS <br />Bureau of Reclamation <br />Southwest Region <br />714 S. Tyler, Suite 201 <br />Amarillo TX 79101 <br /> <br />Final <br /> <br />14. SPONSORING AGENCY CODE <br />SW-720 <br /> <br />IS. SUPPLEMENTARY NOTES <br /> <br />'" <br /> <br />16. ABSTRACT <br />Since 1975, the Western Kansas Weather Modification Project has operated to seed <br />warm-season clouds for hail suppression and rainfall increase. Rainfall data and crop-hail <br />loss data were obtained from 1948-1985 for the target area and for a larger study area that <br />includes parts of six states. Both observed values of precipitation at sites with reasonably <br />long observation periods and interpolations from the observed data fitted to a grid <br />(IS-minutes of latitude by 15 minutes of longitude between 35.5 and 4loN and 96 and <br />l040W) were examined. Hailloss-cost data were fitted to the same grid. Results show that <br />any changes in rainfall due to the seeding program are much smaller than the natural <br />variations that took place. Much of the target area had less growing-season rainfall during <br />the seed years (1975-85) than during the no-seed years (1948-74). This fact should not be <br />attributed to the seeding, however, because the same tendency was noted over much of the <br />surrounding study area. Results of the analysis of crop-hail data are consistent with the <br />hypothesis of a hail suppression effect but do not prove that the seeding has suppressed hail. <br />The apparent effect is concentrated in the eastern part of the target area and extends beyond its <br />northeastern boundary. The suggested suppression effect is a reduction in crop-hail damage <br />of some 25 to 50 percent. The part of the target area with the most favorable hail experience <br />during the seed years also shows a tendency toward drier weather during those years, <br />However, an analysis of hail/rain ratios indicates that the tendency toward drier weather was <br />not sufficient to account for the lessened hail damage. <br /> <br />17. KEY WORDS AND DOCUMENT ANALYSIS <br />a. DESCR IPTORS-- weather modification, cloud seeding, hail suppression <br /> <br />~- <br /> <br />.. <br /> <br />b. IOENTlFIERS-- Kansas <br /> <br />c. COSATI Field/Group <br /> <br />COWRR: <br /> <br />SRIM: <br /> <br />19. SECURITY CLASS ,. NO. OF PAGES <br />(THIS REPORT) <br />UNCLASSIFIED <br />20. SECURITY CLASS 22. PRICE <br />(THIS PAGEl <br />UNCLASSIFIED <br /> <br />18. DISTRIBUTION STATEMENT <br /> <br />Available from the Notional Technical Information Service, Operations <br />Division, 5285 Port Royal Rood, Springfield, Virginia 22/6/, <br />