SLOSH Model Hindcast of Hurricane Irene (2011) Surge

Hurricane Irene (2011) had the potential to be one of the most catastrophic New England Hurricanes with devastating wind and surge affecting North Carolina to New York. This impact was never realized as Irene weakened and the strong winds aloft did not efficiently mix down to the surface. Storms that exhibit this characteristic pose a modeling challenge for surge models that use a parametric wind field. If the wind model is not able to capture the inefficient momentum transfer from the gradient level to the surface, surge will likely be overestimated.

This paper analyzes and validates hindcasts of Hurricane Irene's surge using the Sea, Lake, and Overland Surges from Hurricane (SLOSH) model. The SLOSH model is used operationally by the National Hurricane Center and employs a parametric wind field model based on track, radius of maximum wind, and pressure difference between the storm center and ambient environment.

Surge hindcasts are generated with the operational SLOSH model and with the SLOSH model adapted with the wind field model used by catastrophe modeler AIR Worldwide. The SLOSH wind model assumes a surface wind profile in the pressure equation and AIR Worldwide uses the popular gradient wind profile. The surge hindcasts are compared to observed water levels and high water marks.