Relating Total Lightning and Storm Microphysics to In-Cloud Convective Turbulence

Convectively induced turbulence (CIT) has been shown to cause or factor into a large portion of weather-related commercial aviation accidents. Determining areas of CIT is difficult since CIT is a relatively small scale phenomenon. The Federal Aviation Administration issued guidelines for pilots to avoid thunderstorms, but flying around a storm can waste time and money. In-cloud CIT is created by dynamics within the cloud, such as the updraft. These same dynamics promote cloud electrification and subsequently, the generation of lightning. Therefore, lightning may be an indicator of a robust updraft and the likelihood of CIT. With the expected increase in availability of global lightning data through the launch of the GOES-R satellite, this relationship could improve the identification of CIT in otherwise data-sparse locations.

Data from the NCAR Turbulence Detection Algorithm were compared with total lightning data measured by the Colorado Lightning Mapping Array and dual-polarimetric radar data from the Denver, Colorado and Cheyenne, Wyoming WSR-88Ds. This was done in order to determine possible temporal and spatial relationships of turbulence to electrical and microphysical storm properties. In several case studies of severe storms over Colorado, Wyoming, and Nebraska, it was observed that higher total lightning frequencies accompanied higher turbulence intensities. CIT often occurred prior to any lightning discharges. Likewise, lightning was located within the mixed phase region of a storm, while turbulence maxima often extended just above this region. Additionally, turbulence was observed within the storm after the last lightning strike. Results suggest lightning may be indicative of in-cloud CIT.