Casebook 10 May 2005
CSU-CHILL Casebook: 10 May, 2005
Severe thunderstorm warnings due to large hail were initially issued for the greater Longmont area around 2300 UTC on the afternoon of 10 May 2005. This thunderstorm activity moved northeastward and reached the CSU-CHILL radar site around 0105 UTC on 11 May. (Approximately one inch diameter hail was observed at the radar.) Several polarimetric hail signatures were apparent as the storm approached the radar. At low elevation angles, a minimum was present in the high reflectivity core at azimuth 241 degrees / range 30 km at 0027 UTC. (See VCHILL example below.) Reductions in to ~0.90 can occur when mixtures of large hailstones and raindrops exist in the radar pulse volume. This hail signature passed over the greater Johnstown area where hail diameters of up to 1.25 inches were reported.
