Developing tornado debris signature and ZDR column algorithms for use in the WSR-88D network

With the nationwide implementation of dual-polarization technology in the WSR-88D radar network, the National Severe Storms Laboratory continues to develop algorithms relevant to operational meteorologists and users. This presentation will focus on two recently-developed algorithms. The first algorithm is a modified version of the hydrometeor classification algorithm (HCA) that includes a tornado debris signature class. Whereas the current HCA tends to classify TDSs as either "rain/hail mixture" or "unknown", the changes to the HCA now explicitly allow for a TDS designation. In addition to TDS detection, an algorithm to detect and quantify vertical extensions of enhanced differential reflectivity (i.e., ZDR columns) associated with convective storm updrafts has recently been developed. Although common sampling strategies complicate the detection of ZDR columns, the algorithm is designed to provide additional information about the evolution of convective storm updrafts. In addition, the ZDR column algorithm has the potential to positively impact radar data assimilation owing the relationship between updraft intensity and ZDR column depth.