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I I I I I / II I II I J I I I I I I I I VI. RAINFALL DISTRIBUTION As was mentioned in the previous section, large-scale circulation patterns develop in the atmosphere which helps regulate thunderstorm = rainfall responses. When large-scale upper air patterns persist, the local rainfall response tends to become somewhat repetitive. Some factors influencing locally persistent weather patterns have been discussed before, important among them are: low-level moisture advecting into a region, sufficiently high surface temperatures, convergence features such as fronts and upper troughs and the frequency of jet stream maxima overhead. For much of the summer of 1994 there was a persistent upper air high pressure ridge centered over the western and Intermountain states resulting in a very dry summe.r for them there (few will forget quickly the news reports of the 'great number of forest fires and the tragic deaths of firefighters in Colorado). With the upper ridge to the west of Western Kansas, excessively higher amounts of low-level moisture were fed into the region by easterly-component low-level winds, similar to last year. Also, greater than normal moisture regularly drifted into the plains of eastern Colorado creating favorable conditions for early afternoon convective thunderstorm development aided by above average intense surface heating. Subsequently, the usual easterly-component storm movements were driven by upper winds more usually in a direction to the southeast or east-southeast or, for those storms intensifying strongly, more to the right of their prevailing storm track; hence, severe storms moving out of Colorado and Nebraska cut swaths across our target area tracking to the ESE, SSE or, at times, nearly North-South. The frequency of storms passing through Western and Southwestern Kansas kept these western Kansas counties generally more moist than most other parts of the state to the east as shown in the moisture indices shown in Figures 6 and 7. 1994 long-term and short-term moisture trends are shown in the Drought Severity and Crop Moisture indices presented in the "~"'eekl v Weather and Crop Bulletin" (Figs. 6 and 7). By April 30th almost all of Kansas was "Favorably Moist" in its short-term moisture index, but "Moist" on the long-term index. By mid-September large parts of Central Kansas, short-term, were in an excessively dry condition with moderate drought showing up on the long-term index over the same general region. Whereas, by mid-September Western Kansas \'las slightly dry and Southwestern Kansas more favorably moist, short-term, while at the same time both West and Southwest Kansas remained barely in the Moist Spell category. The 1994 growing season differed from other years yet it was similar in other ways. It was typical insofar as the distribution of rainfall and its occurrence was concerned. There was little winter snow or precipitation, however, rainy periods increased on schedule as it usually does in April-May; storm frequency peaked in 24