An Experimental Hurricane Wind Intensity Size Index (HWISI)

This presentation describes the development and components of a new experimental index of the potential risk posed by the winds in hurricanes. The Saffir-Simpson Scale has provided a widely used index for classification of hurricanes based on their maximum sustained wind speed. The Saffir-Simpson Scale works very well for more intense hurricanes. However, for storms like Hurricane Sandy where the unusual size of the circulation contributes to the damage potential, an index that includes some measure of the size of the storm might provide additional information.

The experimental index is based on the sum of an index that is based on the maximum sustained wind speed and an index based on the radii of 64 kt wind, 50 kt wind and 34 kt wind. The Hurricane Intensity Index (HII) is scaled such that a maximum sustained wind speed of 200 m.p.h. is equal to 50.0. The Hurricane Size Index (HSI) is scaled so that a hurricane approximately the size of Hurricane Sandy is equal to 50.0. The Hurricane Wind Intensity Size Index (HWISI) is equal to the sum of HII and HSI.

The HWISI was computed for Atlantic hurricanes between 2004-2013. The highest index was 73.2 for Hurricane Katrina at its peak intensity. Results for a number of hurricanes will be presented. In addition the HWISI just prior to landfall will be compared to the damaged caused by hurricanes that hit the U.S. during that ten year period.