The Evolution of Lightning Flash Density, Flash Size, and Flash Energy During Hurricane Dorian's (2019) Intensification and Weakening Geophysical Research Letters

The two most distinct inner-core lightning outbreaks in Hurricane Dorian (2019) are analyzed using the Geostationary Lightning Mapper (GLM). The first outbreak occurred during Dorian's intensification, including a rapid intensification (RI), and the second occurred during weakening. During RI, inner-core lightning flash density increased as flashes concentrated inside of the radius of maximum wind (RMW). As weakening commenced, numerous flashes still occurred within the RMW, with a flash rate more than three times that during RI–a signal typically associated with strengthening. These flashes, however, were much smaller and less energetic than those during intensification. Evidence is presented that barotropic mixing and secondary eyewall formation increased the number of small, low-energy lightning flashes in the inner core while simultaneously weakening the storm. The results suggest that flash area and energy from GLM could help distinguish between lightning outbreaks that correspond to intensification and those that correspond to weakening. Grant no. NA14NEWS4320003 Grant no. NA14OAR4320125