Verification of VIPIR Shear Detection Algoritm using multiple WSR-88D radars during 8 April 1999, 2 July 1999 and 11 May 2000 Iowa Supercell Storms

The VIPIR (Volumetric Imaging and Processing of Integrated Radar) computer system is in operational use by the broadcast media in the United States. The system calculates areas of gate to gate cyclonic wind shear greater than 50 kts in convective storms and provides visual notification by generating a rotating "shear marker" on the radar display. The VIPIR system is unique in that its calculations are not limited to a single radar, instead using data from multiple WSR-88D radars and additional data from C-band Doppler radars operated by the media. While the VIPIR system has been heavily promoted in the broadcast industry for its ability to detect and display developing tornadoes and damaging rotating winds, little actual verification work has been conducted to correlate the computer generated shear markers with tornado occurences. In this paper, we will examine the effectiveness of the VIPIR system during three supercell events that occured in Iowa between April 1999 and May 2000 and compare the VIPIR output to the WSR-88D TDA (Tornado Detection Algorithm). Data from a mini-supercell tornado outbreak, a classic supercell event occuring nearly equidistant between three Doppler radars, and an elevated supercell case will provide an initial sampling of the VIPIR capabilities and limitations with varying atmospheric conditions.