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Hurricane Iselle
Status: Closed
| Type of posting | Posting date(EST): | Summary | Downloads |
|---|---|---|---|
| Landfall | 8/8/2014 1:30:00 PM |
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| Pre-Landfall 2 | 8/7/2014 1:23:00 PM |
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| Pre-Landfall 1 | 8/6/2014 12:30:00 PM |
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Pre-Landfall 2 | Summary
Posting Date: August 7, 2014, 1:23:00 PM
Hurricane Iselle continues to head directly for the Island of Hawaii (the Big Island), where it is expected to reach the coast just south of Hilo, the island’s largest community, at about 8 p.m., August 7, local time (06:00 UTC, August 8). No part of Hawaii has been under a hurricane warning since Hurricane Fernanda veered away from the islands in 1993, but Iselle is expected to make landfall as a Category 1 storm, and in doing so would become the first recorded hurricane landfall on the Big Island of Hawaii. Some computer models however show slightly higher shear over the next few hours, which could weaken Iselle to a strong tropical storm prior to landfall.
Meteorological Forecast
Because the wind shear near Iselle is now weaker than previously forecast, and the storm is less than a day from landfall, it is currently projected to reach the Big Island as a Category 1 storm with sustained winds of 80 mph.
Iselle is being steered by a mid-level ridge to the north, and its track remains consistent with recent forecasts and is in good agreement with the multi-model consensus. Its intensity is expected to weaken only slightly before landfall. Interaction with the terrain of the Big Island is expected to weaken Iselle further, and tropical storm conditions are expected to spread to Maui County tonight and to reach Oahu on Friday.
Expected Impacts
Iselle’s winds will likely damage some structures, particularly those not built to current building codes or standards (the Hawaiian islands have been using ICC based codes since 2008). Power transmission poles may be downed and in locations where the ground is saturated, trees may also be downed, which will likely result in power outages. Older homes, or homes not constructed to the building codes in force, may have damage to shingles, siding, gutters and windows, especially if these items are not properly attached. Loose outdoor items, along with damaged roof covering material or damaged wall siding, can become airborne, causing additional damage to neighboring structures and possible injury.
The geographical characteristics of the Hawaiian islands can enhance the destructive power of tropical cyclones. The steep volcanic peaks of Hawaii channel strong winds, increasing wind speeds in the valleys. Winds affecting the upper floors of high rise buildings will be significantly stronger than those near ground level.
In addition, tropical cyclones often bring torrential rains that pour down the mountains, causing flash flooding and severe erosion at lower elevations. Iselle could deposit widespread rains of 4-8 inches over the islands, with some areas seeing as much as 8-16 inches. Especially when combined with astronomical high tides, elevated surf of 10-20 feet and higher may cause coastal erosion, flooding, and property damage along low-lying areas, particularly on the windward side of the Big Island.
The AIR tropical cyclone team is carefully tracking Iselle and will provide updates as warranted. AIR has begun running the AIR Tropical Cyclone Model for Hawaii. If the storm makes landfall as a hurricane and a full loss posting is warranted, AIR will provide event sets to ALERT subscribers early next week.