How Hurricane Wilma Bounced Back to Batter Florida

Willie Drye
for National Geographic News

October 25, 2005

As Hurricane Wilma pelts the U.S. Northeast with winds and rain, more
than six million Florida residents are without power today and picking
up the pieces from the eighth powerful hurricane to strike the state
since August 2004.

Florida residents had been expecting winds of perhaps 110 miles (177 kilometers) an hour, so Wilma's power when it came ashore yesterday at Cape Romano on Florida's southwest coast surprised many people.

"I kept thinking, What happened to the weakening storm?" said Palm Beach Post reporter Eliot Kleinberg, author of Black Cloud: The Deadly Hurricane of 1928.

Wilma was a cantankerous and unpredictable storm almost from the moment it began as a tropical depression in the Caribbean Sea on October 15. During the next ten days it would cut a swath of destruction from Mexico's Yucatán Peninsula to Florida.

The storm's resurgence was difficult to foresee, because Wilma managed to avoid obstacles—such as land and a jet stream—that would have weakened any normal hurricane.

Record Breaker

On October 17, while it was still in the Caribbean, Wilma became the most powerful hurricane ever to form in the Atlantic Ocean. Its winds reached 175 miles (282 kilometers) an hour, and its barometric pressure dropped to 26.04 inches, or 882 millibars.

A hurricane's barometric pressure is a highly reliable indicator of its intensity. Extremely powerful hurricanes such as Wilma have very low barometric pressure readings.

Wilma had lost some of its strength by the time it reached the Yucatán Peninsula on October 21. But the storm still pounded Mexico for two days with winds as strong as 145 miles (233 kilometers) an hour and about 5 feet (150 centimeters) of rainfall.

Sticking to Its Power Source

Keith Blackwell is a hurricane researcher at the University of South Alabama's Coastal Weather Research Center in Mobile. He said Wilma's landfall on the Yucatán Peninsula could easily have weakened the storm quite a bit. But the hurricane didn't push very far inland.

A part of the storm's circulation stayed over the water—a hurricane's power source—during its lingering, destructive Mexican visit.

"It stayed near the coast and kept a large part of its circulation intact," Blackwell said. "It came off the Yucatán very well organized."

Initial forecasts by the National Hurricane Center in Miami, Florida, predicted that Wilma would come ashore in Florida as a Category Two hurricane on the Saffir-Simpson scale. The scale ranks hurricanes from one to five, according to wind speeds and destructive potential.

A Category Two hurricane has winds of 96 to 110 miles an hour (155 to 177 kilometers an hour).

But Wilma was actually gaining strength when it reached Florida, said Jack Beven, a hurricane specialist with the National Hurricane Center. The hurricane's winds of 125 miles (201 kilometers) an hour made it a Category Three hurricane.

Deflecting a Jet Stream

Beven said a seasonal jet stream moving south could have prevented Wilma from strengthening, but the strong winds did not affect the hurricane after all.

Blackwell, of the Coastal Weather Research Center, said Wilma was strong enough to repel the jet stream's winds.

Two of Wilma's characteristics made it typical of storms that often form in October, Blackwell said.

First, it formed in the Caribbean, where the water is still warm enough at this time of year to stoke hurricanes. And its encounter with the seasonal jet stream near the Gulf of Mexico turned it into a fast-moving storm—something that often happens to October hurricanes, he said.

Unusual Aftermath

Hurricane Wilma's aftermath in Florida, however, was unusual.

Often a hurricane leaves behind stiflingly hot, humid weather that puts tempers on edge. But a cold front followed right behind Wilma's departure.

Kleinberg, the Palm Beach Post reporter, said that, aside from not having electricity, conditions in South Florida today are "really quite pleasant."

"The county emergency management people are handing out water and ice, and the nice weather is keeping tempers down," he said.

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

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