Blackwell said the storm would lose much of its intensity over Mexico and would probably not be able to re-strengthen very much when it moves into the Gulf of Mexico.
Had the storm avoided the peninsula and passed through the Yucatán Channel into the Gulf, it would have retained more of its strength as it turned toward Florida, he said.
Wilma will encounter less favorable conditions when it crosses into the Gulf of Mexico. Roberts, the National Hurricane Center forecaster, said upper level winds, known as windshear, will diminish the hurricane's strength even more.
National Weather Center forecasts predict Hurricane Wilma could have winds of about 110 miles an hour (177 kilometers an hour) by the time it reaches Florida.
Blackwell said the storm probably would move very quickly across Florida, and that rapid movement will reduce the amount of damage and rainfall it inflicts.
The hurricane could make landfall anywhere from Florida's southwest coast to the Florida Keys. Officials in Monroe County, which includes the Keys, have ordered all tourists off the islands and have closed all state parks. But a mandatory evacuation of residents has been postponed.
Jeffrey Pinckus, mayor of the Keys city of Marathon, said the storm has inflicted a serious blow to the islands' tourism-driven economy.
"I don't see a lot of tourists on the street any more," Pinckus said this morning. "Every hotel in Marathon is vacant. At the earliest, they won't be back open until late Monday or early Tuesday. That puts a crimp in our business."
Pinckus said that on a normal day during tourist season, visitors spend about $380,000 (U.S.) in Key West, the islands' largest city.
Key West's annual Fantasy Festwhich Pinckus described as "our version of Mardi Gras"was scheduled for this weekend.
The event would have drawn tens of thousands of visitors and poured millions of dollars into the islands' cash registers. But Hurricane Wilma has forced a postponement.
Hurricane Wilma is the 21st storm of the 2005 hurricane season, tying the previous 1933 record for number of storms in a single season. The Atlantic hurricane season officially ends on November 30.
Willie Drye is the author of Storm of the Century: The Labor Day Hurricane of 1935, published by National Geographic.
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