Impact of WSR-88D scanning strategies on severe storm algorithms

The operational meteorological community generally recognizes that the grea ter spatial and temporal resolution of WSR-88D volume coverage pattern (VCP ) 11 is preferable to VCP 21 when using algorithms to identify severe storm characteristics. The coarser vertical sampling of storms with VCP 21 likel y produces less accurate results. An experiment was conducted to investigat e the comparative effects of VCPs 11 and 21. Since VCP 21 is nearly a subse t of VCP 11, the appropriate elevation angles were deleted from two VCP 11 datasets to produce proxy datasets for VCP 21 (called VCP 22). Various WSR- 88D operational algorithms and National Severe Storms Laboratory prototype severe storm algorithms were run on the VCP 11 and VCP 21/22 datasets. At h eights above 5 degrees elevation angle, where VCP 21/22 had missing elevati on angles relative to VCP 11, the majority of algorithm parameters had diff erent values at least 50%-70% of the time. Therefore, this study confirms t hat VCP 11-not VCP 21-should be used in those convective storm situations w here there is a contribution to critical warning parameters from elevation angles greater than 5 degrees.