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Gustav Now Major Hurricane -- And Picking Up Steam

Willie Drye
for National Geographic News
August 30, 2008
 
Declared a Category 4 storm Saturday afternoon, Hurricane Gustav continues to strengthen and will soon reach Category 5 status—the highest—according to U.S. officials.

Gustav is poised to deliver a punishing blow to western Cuba late Saturday before entering the Gulf of Mexico and passing over a deep, warm current infamous for supercharging storms before targeting the U.S. Gulf Coast (Gulf Coast map).

The hurricane's Category 4 designation came after a reconnaissance flight into the storm reported to the National Hurricane Center in Miami that winds around Gustav's eye had reached about 145 miles (233 kilometers) an hour.

At a teleconference Saturday, National Hurricane Center director Bill Read said he is going to raise Gustav to Category 5, though he has not yet done so, according to the Associated Press.

Cuba in Crosshairs

Saturday afternoon Gustav was in the northwestern Caribbean and headed for Cuba.

Havana and the Isle of Youth [or Isla de la Juventud, south of Havana (Cuba map)] will take a pretty bad blow from this, Read told National Geographic News.

As of 2 p.m. ET today, the National Hurricane Center predicts Gustavs eye will hit the Gulf Coast late Monday or early Tuesday.

Landfall is expected at or near Vermillion Parish, Louisiana, about 115 miles (185 kilometers) west of New Orleans. But forecasters caution that the storm could come ashore anywhere from Alabama to Texas.

Gustav is expected to be at least a Category 3 and possibly a Category 4 hurricane when it reaches the Gulf Coast.

Category 3 hurricanes have sustained winds of 111 to 130 miles (177 to 209 kilometers) an hour. Category 4 storms have winds of 131 to 155 miles (211 to 249 kilometers) an hour (hurricane facts, photos, videos, more).

If the hurricane does touch down at Vermillion Parish, New Orleans probably would not suffer a catastrophic repeat of Hurricane Katrina's devastation almost exactly three years ago. Even so, New Orleans Mayor Ray Nagin ordered a mandatory evacuation Saturday.

(Special report: National Geographic magazine on New Orleans' hurricane vulnerabilities—full article, interactive map, videos, and more.)

Frightening Leap Expected

Forecasters think Gustav will lose some of its strength as it approaches the Gulf Coast on Monday.

On Saturday afternoon, however, Gustav was already undergoing a frightening leap in intensity, even though it hadn't yet reached the Gulf of Mexico, whose vast stretches of warm water can supercharge storms.

Its in bathtub-warm water now, and its exploding, said Keith Blackwell, a meteorologist at the University of South Alabamas Coastal Weather Research Center.

Soon Gustav will likely reach Category 5 intensity, with winds exceeding 155 miles (249 kilometers) an hour, Blackwell said.

The Loop Current is expected to fuel that intensification. The current is an eddy of very deep, very warm water that moves north from the Caribbean Sea into the eastern Gulf of Mexico before turning southeast and exiting the Gulf via the Straits of Florida (map).

Hurricanes draw energy from water that has been heated to at least 80 degrees Fahrenheit (27 Celsius). The water Gustav will be crossing for the next two days is nearly 90 degrees Fahrenheit (32 Celsius).

The hurricanes strengthening will be aided by the fact that the warm water in the Loop Current goes down several hundred feet. This means that—instead of churning up cooler water that would cause the hurricane to weaken—Gustav will be pulling up warm water, which will further intensify the storm.

Some Weakening Before Gulf Coast Hit

Blackwell and other forecasters think Gustav will lose at least some of its fearsome power as it draws closer to the Gulf Coast.

For one thing, the water closer to shore will be a little cooler. For another, the storm will come under the influence of wind shear—changes in upper-level wind speed or direction—which will disrupt the hurricane and cause it to weaken, the forecasters say.

Furthermore, if tropical storm Hanna strengthens enough, it could push Gustav back into the Gulf of Mexico after the hurricane has made landfall, Blackwell said. On Saturday afternoon, Hanna was in the Atlantic Ocean north of Puerto Rico and moving west toward the Bahamas.

Hurricane Gustav began Monday as a tropical depression in the eastern Caribbean Sea. It quickly strengthened to a hurricane, then weakened into a tropical storm after crossing mountainous Haiti and the Dominican Republic. Gustav later regained intensity after it met open water again.

The storm may have killed nearly 70 people in its trek across the Caribbean.


Willie Drye is author of Storm of the Century: the Labor Day hurricane of 1935, published by National Geographic Books.

HURRICANE BASICS




Hurricane Facts
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New Orleans' Faulty Levees (National Geographic Magazine)
Forecasting Killer Hurricanes (National Geographic Magazine)
 

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