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The science Says: Hawaii hurricanes rare, but increasingly less so

WASHINGTON – Hurricanes rarely get the near of Hawaii and it is even rarer for one of the islands a direct hit.

Hurricane Lane is already flowing and pummelling the island chain, even without reaching land.

The last time a major hurricane hit Hawaii was in 1992, a Category 4 Iniki caused billions in damage. On average, the central Pacific hurricane region, including Hawaii, will see about four or five storms passed through, but that may change with the warming of the earth.

A look at the hurricane season in Hawaii:

WIND IS THE KEY

Usually wind is what keeps storms threatening Hawaii. The most eastern Pacific hurricanes form in the warm waters of Mexico and to the west. But before they get too far, winds and currents generally cause them to return to the coast. The storms that continue a little further to the south are the rare ones that are in the central Pacific ocean, said Princeton University climate scientist Gabe Vecchi.

This year, the wind does not at all send storms to the east. Add to that weaker than normal winds aloft over where aircraft fly — which typically destroy storms. Winds at that level would normally be 23 km / h to 29 km / h (27 to 47 km / h). Now they are less than half as strong, which helps storms to survive, explained the Colorado State University hurricane scientist Phil Klotzbach.

That’s what happened in 2014 and 2015, which is busier than normal year for storms to get close to Hawaii. There were four in 2015 and three in 2014, including Iselle, which hit the Big Island, but it was a weakened tropical storm.

But the central Pacific is a large area and the islands occupy a small area, so most of the storms will probably not come too close.

HOT WATER

Hurricanes are fed by warm water. The temperature of the water in the region is about 2 to 3.5 degrees (1 to 2 degrees Celsius warmer than normal, according to Vecchi. That was also the case in 2014-2015. “We have come to learn that an unusually warm ocean in the subtropical Pacific, will tend to the increase of the number of hurricanes around Hawaii,” Vecchi said.

The Pacific has more storms during a strong El Nino, a beautiful event that heats the water. Meteorologists expect an El Nino to form in the next few months, but now is the El Nino conditions are even more neutral than hot. Vecchi and others attribute the warming of the earth is a natural cousin of El Nino, with the assistance of the climate change. When it comes to the hurricane activity in the central Pacific ocean, warming the north-south weather pattern is much more connected with the cause of more storms than the east-west of El Nino, Vecchi said.

THE SEASON

So far this year, the entire eastern Pacific region, which consists of the central region, is much more active with more storms, stronger and longer lasting ones than normal, Klotzbach calculated . On average, the region is 15 named storms for the entire season. Lane, which formed Aug. 15 far from Mexico, is already the 12th named storm and the second to get close to Hawaii. In contrast, the Atlantic region is carried out around the average for this point in the season, with stormy conditions slow down recently. Storm gets a name when winds reach 39 mph (63 km / h).

August is the biggest month far for the central Pacific hurricanes, compared with September for the Atlantic ocean. The central Pacific hurricane season runs from June to November, just as the Atlantic ocean. The eastern Pacific runs from May to October.

CLIMATE change

While climate scientists are reluctant to link individual weather events or even seasons, the warming of the earth, they can make the connections with extensive detailed studies. National Oceanic Atmospheric Administration climate scientist, Hiro Murakami, Vecchi, and others studied the 2014 hurricane season around Hawaii and thought it was significantly more likely” due to climate change caused by emissions from the burning of coal, oil and gas, with a natural boost from El Nino.

In a study from last year, they are also linked to global warming until 2015, a record number of large storms in the region, including three Category 4 hurricanes in the central and eastern Pacific at the same time. These studies are limited as a result of weak records of storms in the area prior to 1970, Vecchi said.

WHAT TO EXPECT

A lot of climate research, recently forecast that as the world heats up, the world in general and the Atlantic region have fewer named storms, but more intense ones. However, the central Pacific dollar that prediction.

Several studies predict that the central Pacific busier with more storms, stronger storms and more quickly develop of those, Vecchi said. A Murakami study used computer simulations to predict a noticeable increase in storms around the Hawaiian Islands.

It is even more so because of wind and water. The water in the region is predicted to warm faster than elsewhere in the world, because of a weakening of the trade winds, Vecchi said.

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Follow Seth Borenstein on Twitter: @borenbears . His work can be found here .

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The Associated Press Health & Science Department receives support from the Howard Hughes Medical Institute, Department of science Education. The AP is solely responsible for all content.

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