Lightning and Radar Characteristics of Tornadic Cells in Landfalling Tropical Cyclones

Abstract

AbstractTropical cyclone (TC) tornadoes are often associated with lower‐skill forecasts compared to midlatitude supercellular tornadoes. Forecasts may be improved through a greater understanding of their lightning and radar signatures. This study investigates the lightning and radar characteristics of TC tornadic cells for comparison with TC non‐tornadic cells (i.e., strongly rotating cells without tornadoes) and non‐TC tornadic cells using three lightning networks and radar data. These results show that the majority of TC tornadic and non‐tornadic cells are not associated with lightning, although the former subset occurs with lightning more often. TC tornadic cases typically have lightning maximized to its northeast, whereas the non‐tornadic subset is associated with a lower density of flashes that are more symmetrically distributed. TC tornadic mesocyclones also show stronger low‐level rotation and convergence at the time of tornado occurrence compared to non‐tornadic cases. Hourly trends in rotation and convergence show stronger increases before tornado occurrence in both variables for TC tornadic mesocyclones, yielding small, nonsignificant differences with non‐TC tornadic mesocyclones during tornado occurrence. Finally, analysis of lightning throughout the TC shows that tornadic cells often occur on the downwind edge of a broad lightning maximum, whereas non‐tornadic cases occur in the middle of a weaker lightning maximum, with these maxima propagating away from the TC in both subsets.