Multi-Hazard Mitigation Plan: 05. Tropical Cyclones

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Chapter 5:Hazard Analysis—Tropical Cyclones 2Q Contra] Pacific Hurricane Occurrence n , All hurricanes Hurricanes?category 3 4 Month Figure 5-4. Central Pacific Hurricane Occurrences by month 5.3 Probability of Occurrence The Saffir-Simpson Scale classifies the potential severity of hurricanes. However, this scale may not fully address the risk for mountainous Pacific islands such as Hawaii. The Saffir- Simpson Scale was developed for flat coastal areas with a continental shelf where the winds over the land diminish relatively quickly accompanied by heavy rain. In Hawaii,the variable topography accelerates the winds in certain areas such that one area may be receiving wind speeds at a tropical storm level,while another area may be receiving hurricane-force winds. The number of tropical cyclones in the Central Pacific varies from none to ten annually, and few develop beyond the intensity of a tropical storm. The Hawaii Hurricane Relief Fund (HHRF), originally established after Iniki induced insurance companies to drop coverage in Hawaii, produced several studies on the probability of this hazard (including Applied Research Associates, 2001).19 (Other studies by Peterka & Chock have been concerned with estimating hurricane effects through Monte Carlo simulation models and analysis of topographic effects.) 5.3.1 Probabilistic Hazard Analysis and Scenario Simulations Studies sponsored by the NASA Office of Earth Science and the HHRF have developed new models for estimating the long-term probabilities of Pacific hurricanes. As of 2002, a much improved methodology was used by Peterka in Windspeed Mapping of Hawaii and Pacific 19 Applied Research Associates(ARA),2001,"Hazard Mitigation Study for the Hawaii Hurricane Relief Fund"(incorporates part of FEMA-sponsored Iniki Building Performance Report),December 2001. 5-9 Hawaii County Multi-Hazard Mitigation Plan