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<br />of rawinsonde reports (September through April) for 15 stations - <br />14 stations on the High Plains and one station west of the Rocky <br />Mountains. <br />These climatological data showed that seedable upslope cloud <br />systems occurred from 6 to 25 times per year at individual stations, <br />The highest frequencies were in the northern and central High Plains, <br />February had the highest monthly incidence of upslope conditions in <br />the High Plains, although the monthly distribution varied considerably <br />from north to south throughout the entire region. Most seedable up- <br />slope conditions occurred during the morning (the 1200 GMT sounding), <br />Natural .precipitation fell from 55 percent of the shallow upslope <br />storms investigated, but 95 percent of this was of light or very light <br />intensity. Analysis of the precipitation intensities of these cloud <br />systems has shown a direct relationship between precipitation intensity <br />and"cloud thickness within t~ree regions of the High Plains. Similarly, <br />cloud top temperature appears to be inversely re:ated to precipitation <br />intensity in the northern and central High Plains, although the relation- <br />ship is less clear in the southern Plains. <br />The average seedable cloud layer had a base 300 m above ground <br />and a thickness of approximately 2600 m. The lapse rates of these <br />cloud systems differed markedly across the High Plains, with stable <br />lapse rates in the north (generally +0,00 Oc per 100 m to -O,25oC per <br />100 m) and less stable lapse rates in the west and south (-0.2SoC per <br /> <br />/ <br /> <br />36 <br />