Hurricane Severity Index: A Look Back after 10 Years of Operational Use

The Hurricane Severity Index (HSI) has been used operationally by StormGeo since 2006 to categorize a tropical cyclone’s true destructive potential. The HSI is a 50-point scale, with up to 25 points allocated for the maximum sustained wind speed and 25 points allotted for the size of the destructive wind fields.

In this presentation, examples of several past hurricanes will be shown and compared including their total and component values of HSI, Saffir-Simpson Hurricane Wind Scale category, extent of wind fields, storm surge maximum, and total economic impact (loss in dollars). HSI has been used to compare like storms to each other and also contrast storms that may be a similar intensity but have a large difference in the size of strong winds.

HSI is related to the amount of monetary damage that is experienced from a storm because it takes into account the extent of the winds of a storm as well as the intensity. It can be used as an early escalator in a hurricane response plan to respond with even greater urgency ahead of a more major threat from a large, intense hurricane. The HSI size component has also been used in StormGeo’s Hurricane Trigger Reports to indicate the potential threat of storm surge inundation at long lead times for certain surge-prone coastal locations.