Classification of Hurricane Hazards: The Importance of Rainfall

A new hazard index is presented to estimate and rank hurricane severity according to a storm's damage and death toll after landfall on the continental United States. The index uses three characteristic meteorological aspects of hurricanes: wind, torrential rainfall, and storm surge, each with an individual subindex. Rainfall is identified as an important and frequently dominant hazard in terms of damage and death toll, but is not included in any current hazard scales or indices. The new rainfall subindex adopts rainfall intensity, storm rainfall area, and the forward speed of the system to estimate the rainfall hazard. The new hazard index, applied to recent U.S. hurricanes (2003-12), has better skill than existing scales in terms of ranking the severity of the events by both damage and death toll. Further, the index can provide good quantitative estimates of dollar values for damage and death toll, whereas previous models provide only a scale or ranking. The index provides a basis for improved hazard planning and emergency response, and may also be useful for insurance and risk management processes.