2026/07/27 by Nicholas A. Mesa, Benjamin C. Trabing, Michael M. Bell +5
paper · doi:10.1175/mwr-d-25-0270.1
Abstract The Geostationary Lightning Mapper (GLM) provides continuous, high-resolution lightning observations that enable a novel investigation of lightning attributes in pre-tropical cyclogenesis environments. Compositing and tracking methods from the Tracking and Object-Based Analysis of Clouds (tobac) Python package enable the consideration of lightning lifetime alongside GLM-measured area and optical energy. We first apply the object-based framework to lightning observed prior to the formation of Tropical Storm Claudette (2021), a genesis case within range of the NEXRAD network. Colocated ground-based, dual-polarization radar observations suggest that small-area and low-energy lightning is indicative of stronger convection and updrafts, based on composite vertical radar profiles of tobac lightning features. We then apply the physical interpretations of these lightning attributes to lightning 72 hours prior to genesis and within 200 km of the best-track invest center for five North Atlantic disturbances. Developing disturbances include Claudette (2021), Ida (2021), Earl (2022), and Beryl (2024), which we compare against non-developing AL96 (2024). Small-area and low-energy lightning, previously associated with stronger updrafts and convection, is the dominant lightning mode for the four developing cases with large-area and high-energy lightning also identified at various times. Lightning activity appears to be modulated by deep-layer vertical wind shear, and electrified convection coincides with improvements in convective organization in multiple instances. While more work is needed to evaluate lightning attributes across a larger composite of disturbances, this study offers a novel characterization of lightning in pre-tropical cyclogenesis environments for the North Atlantic to aid in the understanding and forecasting of tropical cyclone genesis.