Insights from Geostationary Lightning Mapper (GLM) Flash Extent Density Over GOES-16 CONUS

Abstract:

The GOES-16 CONUS Geostationary Lightning Mapper (GLM) flash extent density (FED) gridded product is composited during July 2018 – June 2020. The FED is the number of spatially coincident lightning flashes in each 2 km grid cell for one minute. The analyses will enable meteorologists to identify seasonal and inter-annual trends and regional distributions which will help forecasters diagnose thunderstorm evolution and the direct threat lightning poses to people and property.

Preliminary results denote seasonal and spatial trends. In December-February 2018-19, convection is confined to the Southern Plains, lower Mississippi River Valley, and the Gulf of Mexico (GOM). The maximum FED over the GOM exceeds 40 flashes and the total FED count exceeds 6000 flashes in southwest-to-northeast oriented bans. In March-May (MAM) 2019, convection spreads to the Plains and Upper Midwest where maximum FED values exceed 10 flashes. In June-August 2019, the northern, western, and extreme southeastern contiguous US experiences at least 60% of their annual (December 2018-November 2019) lightning activity. For example, the Florida Peninsula sees 2000-3000 minutes of lightning activity with over 6000 flashes. In September-November 2019, GLM observed minimal lightning in parts of Alabama, Georgia, and the southern Appalachians. One clear trend is that lightning occurs year round in eastern parts of Oklahoma and Texas, western Louisiana, and Arkansas. The GLM observes a relative maxima 20000+ flashes of lightning over southwestern Louisiana in December 2018-November 2019. Over 30% of the flashes occur in MAM 2019 and the remaining lightning activity is split 10-20 % in the other seasons.