Abstract Tropical cyclones (TCs) and their post-tropical (PTC) counterparts respond differently to surface warming, reflecting distinct thermodynamic and dynamical controls on storm structure and heavy precipitation. To quantify these responses, we developed a dynamically derived wind-based radius (r6) using ERA5 near-surface winds, capturing storm size, heavy precipitation metrics, and translation speed for North Atlantic tropical cyclones from 2001 to 2024. This metric provides a physically consistent framework to characterize storm evolution and track how heavy precipitation responds to warming. During the TC phase, precipitation intensity rises sharply with all temperatures, reaching a median of 21%/K for dewpoint, while the area of heavy precipitation expands by up to a median of 12.5%/K. Overall cyclone size generally contracts, with a median of 6.5%/K for air temperature, although this contraction weakens or reverses at very high sea-surface temperatures, particularly in the Caribbean, producing unusually large, long-lived storms. Slower motion in these warmer, low-latitude regions prolongs precipitation, boosting totals and concentrating heavy precipitation near the storm core. In contrast, PTCs expand but show limited thermodynamic sensitivity, producing broader, asymmetric precipitation fields under faster translation. These results show rapid ocean warming can intensify and prolong TC precipitation, amplifying regional risks in the North Atlantic.
Ali et al. (Fri,) studied this question.