Late yesterday afternoon, a series of severe thunderstorms had lined up along I-70, from Kansas City to St. Louis, reflecting a cold front that stretched across the State. The first storm hit Columbia about 5:30 PM and it looked as if we were in for recurrent episodes throughout the evening.
This initial storm was, indeed, severe, with hail, strong winds and heavy rain. But, as the front inched southward and other storms arrived from the west, their intensity gradually waned; intermittent, torrential rain and frequent lightening were the only threats.
This scenario is typical of clustered, training thunderstorms. The leading storm, feeding on the warm, humid, unstable air ahead of the front, is most severe. However, trailing storms encounter air that has been cooled (and stabilized) by outflow and precipitation from the initial thunderstorm. As a result, they weaken and are less likely to produce large hail and tornadoes. The latter are most often encountered in isolated "supercell" thunderstorms; like compact, terrestrial hurricanes, they feed on the hot, humid air that surrounds them and are not subject to the cooling effect of nearby storms.
