Insight into the Kinematic and Microphysical Processes that Control Lightning Jumps

Abstract

Abstract A detailed case study analysis of four thunderstorms is performed using polarimetric and multi-Doppler capabilities to provide specificity on the physical and dynamical drivers behind lightning jumps. The main differences between small increases in the total flash rate and a lightning jump are the increases in graupel mass and updraft volumes ≥10 m s−1 between the −10° and −40°C isotherms. Updraft volumes ≥10 m s−1 increased in magnitude at least 3–5 min in advance of the increase in both graupel mass and total flash rate. Updraft volumes ≥10 m s−1 are more robustly correlated to total flash rate than maximum updraft speed over a thunderstorm’s entire life cycle. However, peak updraft speeds increase prior to 8 of the 12 lightning jumps examined. Decreases in mean and median flash footprint size during increases in total lightning are observed in all four thunderstorms and are most notable during development stages within the most intense storms. However, this inverse relationship breaks down on larger storm scales as storms mature and anvils and stratiform regions developed with time. Promisingly, smaller flash sizes are still collocated with the strongest updraft speeds, while larger flash sizes are observed within weaker updraft regions. The results herein emphasize the following for lightning jump applications: both the lightning jump sigma level and the resultant magnitude of the total flash rate must be employed in conjunction to assess storm intensity using lightning data. The sigma-level magnitude of the lightning jump is the early warning that indicates that rapid intensification is occurring, while the magnitude of the total flash rate provides insight into the size and maintenance of the updraft volume and graupel mass. These cases serve as conceptual models for future applications of the lightning jump algorithm for hazardous weather monitoring.