Convective rainfall amounts, ice water content and total lightning for individual storms from different climate regions

This study investigates the relationship between convective rainfall amounts, ice water contents and total lightning activity for storms occurring in the High Plains and in Northern Alabama, USA. Polarimetric radar data were used to compute rainfall amounts and ice water contents, total lightning data was available from ground based lightning mapping systems.

It is generally believed that a well developed mixed-phase region is required to produce lightning and several studies have shown good relationships between precipitation ice amounts and total lightning activity. Thus for events in which the rainfall is predominantly from cold cloud processes, total lightning should be a good indicator of rainfall amounts. However, in systems for which warm processes are dominant the utility of lightning in rainfall estimation is considerably diminished. It is investigated herein the degree to which the relationship between total lightning and convective rainfall derived from radar measurements would be strong enough to benefit QPE in the High Plains and Southeastern United States. A good relationship would be useful during severe storm events for flash flood warnings in regions where radar data may not be available. For example, lightning-rainfall relationships may be used to fill in the data gaps where the radar beam is attenuated by strong convection, or blocked by mountainous terrain. Since total lightning measurements are not susceptible to these effects, QPE could be improved by combining total lightning measurements with more traditional instrumentation. This work could have implications for future algorithm developments related to multi-sensor precipitation algorithms that incorporate broader area total lightning information; e.g., from local VHF lightning mapping arrays of the planned GOES-R global lightning mapper.