Changing Hazards from Landfalling Tropical Cyclones in a Warming Climate

Outside of the primary wind threat, severe local weather associated with landfalling tropical cyclones (LTCs) also contribute to substantial loss of life, economic impacts, and critical infrastructure damage. In recent years there has been more attention on the impacts of secondary LTC hazards such as tornadoes, which can develop 24 hours prior to and up to 48 hours after the tropical cyclone makes landfall, and heavy rainfall that can trigger widespread flash floods. When these hazards are compounded, it can complicate evacuation and safety messages given the opposing recommended protective actions. These effects are expected to be amplified by human-caused climate warming resulting in more intense LTCs and their hazards.

The purpose of this study is to understand what changes, if any, may occur in tornado and rainfall production for LTCs in a future climate. Data for this research is acquired from 4 km resolution ensemble model simulations of U.S. tropical storms over a 13 yr period. The tropical cyclones are then placed in a future climate using pseudo-global warming methods, with the RCP 8.5 warming profile from 19 climate models in the CMIP 5 dataset. Since the dataset is too coarse to resolve actual tornadoes, proxies are developed using threshold exceedances of simulated radar reflectivity and maximum updraft helicity, to assess changes between the historical and future simulated LTCs. Storm total rainfall, maximum rain rate, and area of heavy rainfall are analyzed to understand changes in the rainfall hazard. Results from this study will be presented.