Radar-based Investigation of Thunderstorm Outflow Speed vs. Peak Wind Gusts

A previous study investigated the relationship between thunderstorm outflow boundary propagation speeds and associated measured peak wind gusts for a small sample of gust fronts. The average ratio of maximum wind gusts to outflow boundary propagation speed was determined to be 1.5, with values ranging from 1.1 to 2.3; however, all cases occurred on the high plains of eastern Colorado. The current study calculates the same ratio for several additional locations across the contiguous United States in order to assess discrepancies across differing geographical regions and environments. Approximately 30 cases were compiled for 20 different WSR-88D radar sites by collecting local storm reports (LSRs) of measured wind gusts from automated observing stations. Archived radar data were utilized to attain the motion vector for each of the associated gust fronts, which was then compared to the associated LSR. Preliminary results show an average nationwide ratio of 1.7, with individual site averages ranging from 1.2 to 2.3. These results suggest that the relationship between gust front propagation speeds and peak wind gusts may exhibit considerable regional or environmental variability. Applying these results to National Weather Service operations may improve the accuracy of impact-based severe thunderstorm warning tags for wind gusts, better preparing the public and core partners for imminent weather hazards.