Radar Analysis of Vortex Alignment in 2023 Tropical Cyclones

Accurately predicting rapid intensification in tropical cyclones (TCs) remains a formidable challenge. This challenge is further compounded when considering the influence of environmental vertical wind shear, particularly moderate wind shear, on the future evolution of weaker TCs during early-stage development. This study examines the interplay between environmental factors (wind shear) and vortex dynamics (including tilt and precipitation distribution) concerning TC intensification. The research utilizes the TC-RADAR database, a collection of tail Doppler radar data from NOAA’s P-3 Hurricane Hunter missions, and archived ground radar data courtesy of Météo-France and the Mexican Weather Service. The primary subjects of this analysis are Hurricanes Idalia (2023) and Tammy (2023). Both TCs encountered moderate wind shear during their development and were initially misaligned. The evolution of the shear-relative direction of the vortex tilt illustrates the importance of vortex alignment as a crucial process for intensification. A detailed evaluation of directional shear flow demonstrates the important kinematic and thermodynamic differences of asymmetric, tilted TCs and explores the transition to a more coherent, upright vortex structure and axisymmetric precipitation. Multiple physical processes explain the transition from a tilted to a nearly aligned TC vortex; exploring this evolution in Hurricanes Idalia and Tammy suggests important contributions from varying pathways involving both advective and diabatic processes.