Multi-Hazard Mitigation Plan: 04. High Wind Storms

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Chapter 4:Hazard Analysis—High Wind Storms carrying cargo depended on the broad belt of Easterly winds encircling the globe in the subtropics for fast passage. High winds from trade winds, which blow 70% of the time (Kodama 1998), Kona winds (30% of the time), and rare winds from hurricanes and tropical storms passing through Hawaiian waters all affect the island of Hawaii. (Fletcher 2000) Tradewinds predominate from the northeast and generally range from 10 — 25 miles per hour, although occasional extreme events reach 40 - 50 miles per hour. North Pacific High pressure systems are responsible for the majority of the gusty trade wind episodes over Hawaiian waters, which commonly persist for several days before tapering off. Strong, gusty trade winds can cause problems for mariners. These strong trades blowing from the NE through East funnel through the major channels between the islands--Kauai, Kaiwi, Pailolo, Kalohi, and Alenuihaha Channels--at speeds 5-20 knots faster than the speeds over the open ocean. Mariners and beachgoers must exercise good judgment prior to entering the waters exposed to strong trades, especially in the major channels. 2:00 a.m.HST 2:00 p.m.HST • • • _ r— g_ %hafa"+�, • Mad Mautia Kea Huala Huslal r� 0 Mauna� 49a 'lau •IGlauea Example 6.0 rvrvn/svrviJ � � The winds during the day on l lawai'i Island vary in a consistent fashion.These examples show mean wind flows at 2:00 A.M.and 2:00 P.M.,based upon a 42-day sample from 50 portable automated weather stations.The results comply with meteorological predictions for the behavior of air abort a heated island in a trade wind flow. Figure 4-1. Typical diurnal wind patterns on Hawaii Island 4-2 Hawaii County Multi-Hazard Mitigation Plan