Why Hawaiian Hurricanes Are So Rare
The islands are usually protected by their remoteness and a stable high pressure system, which has gone wonky in the last year
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Much of the state of Hawaii is currently under a hurricane warning, with Category 4 Hurricane Lane threatening to make landfall, bringing 10 to 24 inches of rain in some parts of the state, reports CBS News. This is the second hurricane to threaten the Hawaiian Islands in the past month with Hurricane Hector brushing by just a few weeks ago. While hurricanes are common along the United States’ Gulf Coast, the Eastern Seaboard and in the Caribbean, tropical cyclones are almost unheard of in Hawaii. So why are hurricanes in the 50th state so rare?
Rafi Letzer at LiveScience explains that it’s all about wind and luck. The Pacific Ocean is home to some of the worst tropical cyclones ever recorded. In the western half of the Pacific, they are called typhoons instead of hurricanes and tend to be bigger and badder than the storms that plague the Americas. In fact, in terms of wind speed only one hurricane, 2015’s Patricia, even cracks the top ten; all the rest are cyclones in the Pacific and Indian Oceans.
Most of those typhoons form in the Pacific and gain strength while moving west, hitting Australia and east Asia, sparing the Aloha State from the megastorms. Storms with a chance of hitting the islands typically form in the warm waters off the coast of Mexico are blown west by the prevailing winds.
But the Pacific Ocean is massive, and the Hawaiian Islands are not so big, at least geographically speaking: The odds of a hurricane colliding with 10,931 square miles of islands in the 62.46 million-square-mile Pacific Ocean are pretty small. That’s a much harder target to hit than say, the entire eastern edge of North America.
“Hawaii is a small target in the big ocean, so it just has to be really good timing and the conditions have to be right for us to get a direct hit,” Eric Lau, a meteorologist for the National Weather Service in Honolulu, told the Associated Press in 2014, when two hurricanes were barrelling toward at the islands (they missed).
Mary Beth Griggs at Popular Science also explains that for a hurricane to hit Hawaii it has to overcome some pretty stiff winds. Typically, an atmospheric wind pattern shifts the course of any storms heading towards Hawaii, acting like a force field.
“The major reason that Hawaii doesn’t normally get major hurricanes nearby is that there’s a strong subtropical high-pressure system that sits just to the north, and that acts to steer [storms] straight west,” Brian McNoldy, meteorologist and hurricane researcher at the University of Miami in Florida, tells Griggs.
Unfortunately for Hawaii, that high-pressure suit of armor moved west and has been wimpier than normal for the last year, letting the hurricanes in. The waters around the islands are also warmer than usual, adding power to approaching hurricanes. Hurricane Lane escalated to a Category 5 hurricane, the highest level, earlier this week before weakening to Category 4.
McNoldy says there have only been five Category 5 hurricanes recorded in the Central Pacific since record keeping began and none of those have gotten near Hawaii. If Hurricane Lane makes landfall in Hawaii, it will be only the fourth cyclone ever known to hit the island, including Hurricane Iniki that hit in 1992; Hurricane Dot that appeared in 1959; and an unnamed storm in 1871. A couple of tropical storms have also hit the islands, including Tropical Storm Iselle in 2014.
The rarity of hurricanes means the islands, unlike Florida which expects the storms every few years, is not hardened against them. Hurricane Lane is expected to begin affecting the islands today and last through Saturday. Authorities are telling residents outside of flood zones to shelter in place since the islands do not have enough shelter space for all residents. Anyone in the path of the storm should follow all the emergency guidelines issued by the National Weather Service.