AN ENHANCED HAIL DETECTION ALGORITHM FOR THE WSR-88D

An enhanced hail detection algorithm (HDA) has been developed for the WSR-88D to replace the original hail algorithm. While the original hai l algorithm simply indicated whether or not a detected storm cell was producing hail, the new KDA estimates the probability of hail (any siz e), probability of severe-size hail (diameter greater than or equal to 19 mm), and maximum expected hail size for each detected storm cell. A new parameter, called the severe hail index (SHI), was developed as the primary predictor variable for severe-size hail. The SHI is a ther mally weighted vertical integration of a storm cell's reflectivity pro file. Initial testing on 10 storm days showed that the new HDA perform ed considerably better at predicting severe hail than the original hai l algorithm. Additional testing of the new HDA on 31 storm days showed substantial regional variations in performance, with best results acr oss the southern plains and weaker performance for regions farther eas t.