Inland Tropical Cyclone Impacts in a Warming Climate: Semi-Idealized Simulations of Hurricane Fran (1996 and 2096)

Abstract This study examines the factors that affect the inland impacts of landfalling tropical cyclones (TCs), and how they will change in a warming climate. Our focus is primarily on near-surface winds though we also consider the combined hazard of concurrent heavy rain and strong wind. We adopt a pseudo–global warming numerical modeling strategy based on an observed landfalling TC in the southeastern United States: Hurricane Fran (1996). To eliminate the effects of terrain and coastline complexity, an additional semi-idealized ensemble experimental design without terrain and with a straight coastline is used to simulate present-day and future landfalls. The TC in the future ensemble exhibits greater landfall intensity, a smaller radius of maximum wind, and slightly weaker outer-core maximum wind speeds relative to the present-day ensemble. We find that while the TC decay rate increases in the future warmer climate, the inland extent of damaging winds nevertheless increases in the future ensemble due to stronger landfall intensity. Metrics related to the areal extent and coverage of overthreshold values prove to be an important measure of hazards and their change. The area of simulated concurrent tropical-storm-force wind speeds and rain exceeding 25 mm h −1 more than doubles for an end-of-century Fran under a high-emission scenario. Significance Statement The purpose of this study is to better understand how climate change will affect inland tropical cyclone (TC) impacts, specifically changes to the rate of weakening after landfall, the coverage of damaging winds, and the combined occurrence of strong winds and heavy rain. This is important because recent studies have shown that inland TC decay rates may decrease in the future. Our results show that intensity is a leading control for decay rate, and more intense storms decay at a faster rate, leading to an increased decay rate in the future. Despite faster decay, we find increased future coverage of damaging winds and of combined wind/rain occurrence, which would increase TC risk for future inland populations.