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<br />0025G6 <br /> <br />atmospheric soundings, preparing daily weather forecasts and main- <br />taining a weather watch during experimental periods, assisting with <br />operation of a 5-cm digital radar .system, and compiling the data for <br />dissemination to other groups. Postfield season work included the <br />stratification of experimental periods based on the type of cumulus <br />activity observed to partition data for analyses. <br /> <br />Subsequent data analyses indicated that one of the important vari- <br />ables for forecasting deep convection was the amount of precipitable <br />water from the surface to the 700-mbar level. Other parameters that <br />proved to be useful as predictor variables were the forecast 12-hour <br />change in vorticity and the presence of a capping temperature inver- <br />s i on. It was found th at synopt i c features, such as fronts, always <br />need to be considered, as they can trigger convective activity even <br />when insufficient low-level moisture is indicated. Based on these <br />findings, a preliminary forecast decision tree was developed for <br />objectively preclassifying experimental periods during future HIPLEX <br />field experiments. <br /> <br />CONTRACTOR: Environmental Rese.arch and Technology, Inc., Concord, <br />Mass achusetts <br />CONTRACT NO. 14-06-0-7673 <br />PRINCIPAL INVESTIGATOR: C. A. Grainger <br />PERIOD: April 15, 1975 - Continuing <br />FUNDING: FY75 - $ 60,020 <br />FY76 - $255,920 <br />T.Q. - $192,748 <br />FY77 - $351,315 <br />FY78 - $398,221 <br /> <br />The purpose of this contract was to conduct and support weather <br />modification research in Kansas and adjoining states in connection <br />with HIPLEX. The field program consists of a 6-day-a-week operation <br />during the summer seasons, which vary in length from 2 to 4 months. <br />Daily operations consisted of operational forecasting upper air <br />soundings, operating the Skywater SWR-75 radar, maintaining a network <br />of precipitation gages, and making ice nuclei measurements. Aircraft <br />missions were conducted for periods of up to 4 weeks each year. <br /> <br />Analyses have concentrated in five major areas: <br /> <br />(1) Analysis of mesoscale and small-scale synoptic features has <br />identified several parameters which strongly tnfl~ce convection <br />for use in forecasting procedures. These are the equivalent <br />potential temperature field and its gradients, and convergence <br />fields. Analysis of these parameters, when considered with other <br />cloud triggering mechanisms, can be used to accurately predict the <br />onset of convection that will result in precipitation. <br /> <br />III-19 <br />