By contrast, Hurricane Katrina had been a Category 5 storm as it roared toward the Gulf Coast, but had downgraded to a Category 4 when it made landfall near New Orleans in August 2005.
Forecasters think Dean will weaken as it crosses the Yucatan Peninsula today and will emerge into the Gulf of Mexico near Campeche this afternoon (see map).
At that point Dean is expected to be a Category 2 hurricane, with winds of at least 96 miles (155 kilometers) an hour.
The storm could regain strength, however, as it churns toward another landfall Wednesday afternoon about 160 miles (257 kilometers) east of Mexico City.
Forecasters think it will have winds of at least 111 miles (178 kilometers) an hour by then, making it a major Category 3 hurricane as it comes ashore again.
News reports attribute at least 12 deaths to Hurricane Dean since it began its trek across the Caribbean as a tropical depression on August 13.
(See photos: Hurricane Dean Lashes Jamaica.)
Forecasters had expected Dean to reach Category 5 strength sooner, but a phenomenon known as an eye wall replacement cycle kept the storm's winds below that threshold.
In this cycle a second eye wall forms around the storm's existing eye wall and acts as a noose, preventing the hurricane from intensifying. The event occurs only in very powerful hurricanes.
But as Dean approached the Yucatan Peninsula last night, it moved over heated waters and gained strength.
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