A WSR-88D TDA performance evaluation using Level II data from the western/intermountaion U.S.

The WSR-88D Tornado Detection Algorithm (TDA) was implemented into the Build 10 Radar Products Generator in November 1998. Prior to this implementation, the TDA was developed and tested at the National Severe Storms Laboratory (NSSL) using a limited amount of Level II data available from different regions of the US. The overall lack of Level II data from the western/intermountain region of the US as well as quality tornado ground truth information precluded their inclusion into the initial development and evaluation of the TDA prior to its acceptance and implementation into the Build 10 RPG. Tornadoes are rarely observed in the western US region compared to those observed east of the Rocky Mountains. However, since 1995, the full deployment of Level II recorders has afforded the collection of a large volume of WSR-88D Level II data in the western US region. In addition, a relatively large number of reported tornado events in the western US have been captured by these Level II recorders. As a result of the Salt Lake City, Utah tornado event on 11 August 1999, interest was spurned regarding the performance of the WSR-88D TDA in the western US especially given the location of several radars in high terrain and the perceived uniqueness of storm evolution, character and near-storm environments. An evaluation of the WSR-88D TDA using Level II data collected in the western US will be presented. The authors shall discuss the WSR-88D TDA performance in light of observedstorm type as well as the automated detection of tornadic vortices occurring in complex terrain by the WSR-88D. Overall characteristics of the identified/observed vortices shall also be presented.