Empirical Evidence for Gulf of Mexico Hurricane Landfall Dispersion

The clustering of hurricanes throughout the Contiguous United States (CONUS) is a poignant topic for risk carriers with interests throughout the US. Questions often asked include: How likely are multiple hurricane landfalls throughout the US and where would these subsequent landfalls be likely to occur? This study takes an empirical approach to analyse the intra-annual landfall dispersion of CONUS landfalling hurricanes throughout the Gulf of Mexico (GoM). The study finds that local GoM hurricane landfall co-occurrence is likely under-dispersed relative to what one might assume given a Poisson landfalling model. For coastal segments (termed wind gates) of length scale 556 km, this study also identifies the likely over-dispersion of hurricane landfall co-occurrence in the neighbouring wind gates. The author discusses plausible mechanisms, based on the available literature, however, promotes the need for further work into these proposed mechanisms. For insurance risk carriers the results of this study can impact underwriting decisions surrounding premium rates and risk selection, whilst also informing decisions surrounding outwards reinsurance purchasing. More fundamentally, a shift to non-Poissonian GoM hurricane landfall probabilities will likely impact long-term decisions surrounding portfolio management.