Relating Multi-Radar/Multi-Sensor Products to Lightning and Thunderstorm Severity

Lightning is a common and often deadly occurrence in South Florida; therefore, there is an increased need to issue products with respect to excessive lightning production. Recent research has proven that thunderstorm severity is correlated with total flash rates and lightning jumps, making lightning a key variable to use in National Weather Service (NWS) warning operations. Along with continued integration of dual-polarization (DP) radar and Multi-Radar/Multi-Sensor (MRMS) data, forecasters have additional information to understand the charge separation process. One of these MRMS variables, Vertically Integrated Ice (VII), can potentially offer a unique insight by correlating a qualitative conceptual model of charge separation to known quantitative thresholds.

This study examines over 50 cases of isolated summertime convection in South Florida that occurred in May, June, and July of 2017. Box and whisker plots of multiple DP radar, MRMS, and lightning data variables were created and assessed in relation to thunderstorm severity and time to first strike. Preliminary findings show utility in using variables such as a VII maximum value of 5 kg/m2 and average areal coverage of VII ≥1 kg/m2 in excess of 50 sq. km as key discriminators to lightning potential and severity. Predictive equations using regression analysis have also been developed for total possible lightning and time to first strike. One thunderstorm case is presented highlighting a proposed methodology and application of this work. Future work will involve performing a principal component analysis to further refine the results along with the development of a decision aid.