The Structure and Motion of Severe Hailstorms. Part III: Severely Sheared Storms

A case study of a severe hailstorm which occurred in an extremely sheared environment is presented. The storm occurred near Fort Morgan, Colo., on 15 June 1970, and contained a large, persistent bounded weak echo region (WER). The Fort Morgan storm evolved in a manner and displayed several characteristics similar to another storm previously synthesized by Chisholm which also occurred in an extremely sheared environment. It is proposed that the extreme shear probably acted to erode the turbulent air containing precipitation sized particles from around the updraft core, thus allowing the large, bounded WER to persist in each storm. The erosion or detrainment effect is speculated to have accounted for the evolutionary characteristics of these two storms.