During Spring 2004, a new scanning strategy or volume coverage pattern (VCP) will be added to the suite of VCPs 11, 21, 31, and 32 currently in use with the Weather Surveillance Radar - 1988 Doppler (WSR-88D). The new VCP is a modified version of VCP 11 (both with 14 elevation angles) that incorporates features requested over the years by forecasters. The new VCP is faster (completing a volume scan in 4.1 min instead of 5.0 min) and it has denser vertical resolution at lower elevation angles (separated by 0.4-0.5 deg instead of 0.9-1.0 deg).

Field tests of prototype versions of the new VCP were conducted during 1999-2001 in Oklahoma and during 2002 in Mississippi. The field tests consisted of running the prototype versions on testbed WSR-88Ds in Norman, OK and at Keesler Air Force Base, MS and comparing output from severe storm algorithms with algorithm output from nearby operational WSR-88Ds. Algorithm comparisons were made only on storms at medium to far ranges that were equidistant from the testbed and operational radars.

Basic findings show that the greater vertical low-altitude resolution of the prototype VCPs made a significant difference between identification and nonidentification of severe storms by the various severe storm algorithms. When cells or circulations leading to mesocyclones were identified using both operational and prototype VCPs, we found that features were identified up to 10-35 min earlier with prototype VCPs. With earlier identification of a cell, the appropriate algorithms would start sooner producing information and trends concerning parameters such as cell track, maximum reflectivity, vertically integrated liquid (VIL), probability of hail and severe hail, and maximum hail size. With earlier identification of a circulation, one would be alerted sooner to the likely formation of a mesocyclone with its associated strong winds, large hail, and possibility for tornadoes.