The Hurricane Severity Index is a scale that can assign up to 50 points to a system; up to 25 points come from intensity, while the other 25 come from the size of the storms wind field. The IKE model measures the destructive capability of a tropical cyclone via winds, waves, and surge.
ACE is calculated by summing the squares of a cyclones sustained wind speed, every six hours as long as the system is at or above tropical storm intensity and either tropical or subtropical. The calculation of the PDI is similar in nature to ACE, with the major difference being that wind speeds are cubed rather than squared. The Hurricane Surge Index is a metric of the potential damage a storm may inflict via storm surge. It is calculated by squaring the dividend of the storms wind speed and a climatological value (33 metres per second (74 mph)), and then multiplying that quantity by the dividend of the radius of hurricane-force winds and its climatological value (96.6 kilometres (60.0 mi)).