Hurricane Lane, once a Category 5, fell apart as it inched closer to the Hawaiian Islands from the south. Despite Lane’s beautiful collapse, this storm brought several feet of rain to some parts of the Big Island. Before Lane’s landfall, emergency officials were urging residents to gather supplies and prepare their property for the storm’s impact, producing scenes we normally associate with the Gulf region of the United States. But, why is it so unheard of for Hawaii to find itself in the path of a major hurricane? After all, Hawaii is an island state resting in the middle of the Pacific Ocean, where Pacific storms consistently reach extreme intensities farther to the West. However, Hawaii has only experienced landfalls from two hurricanes and two tropical storms since 1959. In 2014, it appeared that two hurricanes were on course to hit Hawaii back-to-back. Thankfully, one of the then-hurricanes, Iselle, was downgraded to a tropical storm before making landfall; Iselle’s twin, Julio, moved too far north, missing the islands.
It turns out Hawaii is in a “sweet spot” for a few reasons! Geographically speaking, the Pacific Ocean is exceptionally large (62.46 million-square-miles) while the Islands are quite small (10,931 square miles). Thus, the odds of a major hurricane striking such a small target is low, especially when compared to the odds of a hurricane striking along North America’s Gulf Coast or East Coast. In order for a hurricane to make direct landfall with Hawaii, the atmospheric conditions have to be perfect.
Throughout May and October – peak hurricane season – a strong subtropical high-pressure feature sits to the north of Hawaii, acting as a barrier and driving storms westward. Cooler ocean waters to the north and east of the Hawaiian Islands also help to protect the region. Most years, the ocean temperatures are too cool for intense tropical systems to strike from the east. We can thank the regional ocean currents for this, as they bring cooler Alaskan waters down and along the eastern Pacific and West Coast regions. Ocean-surface temperatures tend to warm up the further south you go in the Northern Pacific Ocean, meaning a tropical system moving towards the Hawaiian Islands from the south would have a much higher probability of surviving. Any south or southwest wind aloft would help to steer a tropical system towards the Islands. During El Nino years, this situation changes slightly; El Nino allows warmer waters to creep further northward, getting into the tropical east-to-west track of tropical systems coming in from the eastern Pacific. This increase in ocean-surface temperatures also promotes tropical system formation closer to the Islands as well as across the eastern Pacific Ocean. El Nino also lessens the trade winds that occasionally decrease tropical activity, allowing tropical activity to the south to be drawn northward.
Despite their rarity, when strong hurricanes strike Hawaii, they are often very damaging. In 1992, Hurricane Iniki – the most powerful Hawaiian hurricane (pre-Lane) – killed six and injured over 1,000 people, causing $1.8 billion in damages. Unlike the Gulf and Eastern Coast, large-scale evacuations are immensely challenging due to Hawaii’s remote, cramped geography. Unfortunately, this means that when a major tropical system is charted to strike Hawaii, many are left without shelters. According to a recent report, Hawaiian officials believe that when it comes to seeking shelter, most people would be left to fend for themselves. While most of the Island chain’s shelters are comprised of public schoolhouses, officials fear that these buildings – which are not always up to code due to high inspection costs – would not be able to withstand a major storm.
Thankfully, Hurricane Lane dissipated greatly before striking the Hawaiian Islands. Lane was also bombarded with vertical wind shear and dry air which attacked Lane’s core, leading to the storm’s demise. Although Lane produced severe flooding and landslides on the Big Island, the storm surge and extreme winds were lessened, sparing the Islands from devastating wind damage.
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© 2018 Meteorologist Ash Bray