Hawaii Often Protected From Hurricanes
Updated August 17, 2011
By WeatherBug Meteorologist, Andrew Rosenthal
Hawaii, a tropical paradise in the central Pacific, rarely sees hurricanes and tropical storms. While this may seem a bit strange at first, consider the Islands` location. A protective shield of colder water and strong upper-level winds keep most storms at bay. That said, the Aloha State is not immune to hurricanes, and remains exposed to storms that arrive from the south.
In general, hurricanes and tropical storms thrive on the warm water of the tropics, with sea-surface temperatures of 80 degrees typically needed to maintain a hurricane`s strength. During the summer months, Pacific water temperatures this warm are found along the Mexican and Central American coast as far north as southern Baja California. But further off the coast, the deep Pacific Ocean circulates cooler water to reach the surface in a process known as "upwelling." Hawaii is located on the edge of one of these deep ocean trenches which stretches for about 1,000 miles to the east, and as a result some of the water off of the Hawaiian Islands is as warm as the upper 70s near Hawaii. While these water temperatures are comfortable for swimming, they are poison to most hurricanes.
Generally speaking, a hurricane or tropical storm will travel east-to-west, directed by the tropical trade winds. However, as it is affected by cooler water, it becomes increasingly susceptible to winds coming from any other direction, which act to slowly tear the storm to bits. Thus, a storm traveling directly from the east toward Hawaii stands little chance of surviving its journey across the cool central Pacific.
This was the path attempted by Hurricane Felicia in early August 2009. At one time, Felicia was a monstrous Category 4 hurricane with winds of 145 mph. This prompted landfall concerns as it spun westward toward Hawaii`s Big Island. However, as Felicia crossed the Central Pacific, it slowly started to weaken over the cooler water, and then was pulled northward and shredded as it encountered wind shear about 400 miles to the east of Hawaii. By the time the storm approached the Aloha State, it possessed little of its former power.
This is not to say that Hawaii is completely protected from tropical storms. There is one direction in which the Islands are susceptible to a hurricane invasion: from the south.
The pool of warmer water remains intact across the Pacific between 500 and 750 miles south of the Hawaiian Islands, and a hurricane which forms and moves due westward about 600 miles south of Hawaii can maintain its strength into the central Pacific. If winds direct the storm northward toward the Islands, it has a chance to survive.
This path was taken in 1992 by Hurricane Iniki, which moved west across the central Pacific along this route, then made a right-hand turn to the north and sliced a path across Kauai, one of the western islands in the chain. Iniki made landfall as a Category 4 hurricane, packing winds of 140 mph. Its destruction was immense, with nearly 5,000 houses damaged and another 1,400 destroyed.
WeatherBug Meteorologists continue to watch the waters off Hawaii as well as the eastern Pacific and Atlantic basin to give you the latest on the tropics. Be sure to keep WeatherBug active to receive the latest weather in your neighborhood. Get the latest updates anywhere on Twitter
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