for National Geographic News
The warm waters and current "soft and stable" upper atmosphere in the Gulf of Mexico could transform Hurricane Ike into a major hurricane as it heads toward Houston, forecasters say.
As of Monday afternoon the storm was about 250 miles (402 kilometers) east of Havana, Cuba, and careening westward across the island country.
It struck Cuba on Sunday as a Category 4 hurricane with winds of more than 131 miles (211 kilometers) an hour.
Eastern Cuba's high mountains weakened the system to a Category 2 hurricane, with winds of about 100 miles (161 kilometers) an hour around its center.
Forecasters suspect Ike will weaken to a Category 1 hurricane with maximum winds of 95 miles (153 kilometers) an hour or lower by Monday night.
(Related: "Hanna, Hurricane Ike Take Aim at Eastern U.S., Bahamas" [September 5, 2008].)
Once in the Gulf of Mexico late Tuesday, the storm will cross the storm-fueling Loop Current—an eddy of very deep, warm water that circulates through the Gulf during the late summer—said Paul Lewis, a meteorologist at the Houston-Galveston National Weather Service office.
Hurricanes draw their energy from ocean waters that have been heated to at least 80 degrees Fahrenheit (about 27 degrees Celsius), and the temperature in the Loop Current is currently higher than 85 degrees Fahrenheit (about 30 degrees Celsius).
The five-day forecast from the National Hurricane Center predicts that Hurricane Ike will be just offshore of Houston on Saturday morning, threatening that city as a Category 3 storm, with winds of 111 miles (179 kilometers) to 130 miles (209 kilometers) an hour.
But Felix Garcia, a meteorologist at the National Hurricane Center in Miami, said Ike could possibly intensify to a Category 4 hurricane. Category 5 is the highest storm rating. Any storm Category 3 and above is considered a major hurricane.
"The upper atmosphere is pretty soft and stable, no strong winds to break it apart," Garcia said. "We are expecting Ike to be near the U.S. as a Category 3 or maybe a Category 4."
The last major hurricane to directly strike Houston was Hurricane Alicia in 1983, which made landfall as a Category 3 storm, the National Weather Service's Lewis said.
But forecasters caution about drawing conclusions five days out, emphasizing the average margin of error is about 300 miles (483 kilometers). Hurricane Ike could make landfall anywhere from the Florida Panhandle to the U.S.-Mexico border.
Near Miss in the Keys
Meanwhile officials in the Florida Keys suspended an evacuation today after the forecast track for Hurricane Ike moved farther to the south.
Emergency-management officials on the low-lying islands ordered a mandatory evacuation of tourists and residents late Friday afternoon when Ike was expected to make landfall near the town of Marathon as a Category 4.
Although Ike is expected to remain south of the Keys, officials were also concerned that the storm would bring high winds and flooding on U.S. 1, the only highway out of the islands.
Willie Drye is author of Storm of the Century: the Labor Day hurricane of 1935, published by National Geographic Books.
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