Low-Level Wind and Moisture Variations Preceding and Following Hailstorms in Northest Colorado

Abstract

The evolution of the mean low-level environmental wind and moisture content at Sterling, Colorado, on days preceding, during and following hail episodes has been determined from National Hail Research Experiment soundings. Results show marked development of shallow easterlies during had days compared to mean westerlies on no-hail days. Southerly wind components increase for thundershower and bag days as early as 24?36 h prior to the event, compared to little change during no-hail periods. Moisture content increases am in concert with increasing southerly and easterly winds. Southerly winds diminish or become northerly during the 12?24 h after the hailfall event. An example of evolving low-level wind and moisture content accompanying a notable hail outbreak?including the Fleming storm?is presented.