This is why the term cold air funnel got its origin. This process is similar to that shown by research meteorologists in the formation of landspouts which typically form on the High Plains. Cold air funnels generally are weak, short lived, and usually do not touch down. One of the reasons that they do not touch down and, by definition become a tornado, may be that there is little rainfall associated with these storms to produce a downdraft in order to generate a low level circulation. Recent research suggests that the interaction of descending rainfall near the surface and the thunderstorm updraft may be very important in generating a low level circulation which links with the upper level mesocyclone circulation to form the tornado in typical severe thunderstorms.
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