Quantifying the Benefits of a Simulated Rapid-Scan Weather Radar for Severe Storm Observations

Over the past several years, intense study and planning have been underway to design a viable replacement system for NEXRAD. Ideally, such a system would offer improved temporal resolution compared to NEXRAD, on the order of 1 min for high-resolution weather data. In this study, the benefit of rapid-scan data is assessed by comparing the effect of scanning strategies on tornadic debris signature (TDS) detection latency time, where latency time is defined as the time lag between the earliest lofting of debris by the tornado and the initial appearance of a TDS detected by the radar through an objective detection algorithm.

This study shows that the calculated difference in TDS detection latency time (137-207 s) is greater than the theoretical improvement based on the difference in VCP update times (107 s). This result is consistent with results from a previous study on the effects of a rapid-scan radar on the issuance of low-level wind shear warnings. The statistical significance of this result is tested with bootstrapped means. This significance test indicates that the improvement in TDS latency time (compared to the theoretical improvement) is statistically significant. This effect is most pronounced at lower debris concentrations; it is theorized that this is due to debris lofting being more transient in simulations with lower debris concentrations, leading to greater fluctuations in TDS area with time. If this hypothesis is true, it would mean that faster update times should provide the most detection lead time benefit in tornadoes with weaker TDSs. It is believed that the results from this study can help inform decisions about the temporal update requirements of a NEXRAD replacement system.