Doppler radar analysis of a severe spring snowstorm

A major winter storm occurred over the Central Plains of the U.S. on 4-7 March 1989. The snow storm occurred during a field experiment conducted by the University of Illinois at Urbana-Champaign to study the mesoscale dynamics of the winter storms in the midwestern United States. The University of Illinois Winter Precipitation Program (UNIWIPP) made use of the 10 cm Doppler CHILL radar, then operated by the Illinois State Water Survey, a Cross Chain Loran Atmospheric Sounding System (CLASS) balloon sounding facility, and an array of surface measurement instruments during this storm. We were able to document the mesoscale eveolution of this storm for its duration over Illinois with the CHILL radar. When echo areal coverage was sufficiently large, sequential PPI scans, stepped to 90 degree elevation, were performed to deduce the local wind field kinematic properties using Extended Velocity-Azimuth Display (EVAD) techniques. The cycles of CHILL scan sequences were repeated every 10 to 20 minutes throughout precipitation periods.