for National Geographic News
Gaining power up until the moment it touched land, Hurricane Dean struck the southern Yucatan Peninsula early Tuesday with winds of 165 miles (265 kilometers) an hour.
Dean came ashore as a Category 5 hurricane, a classification reserved for the most intense storms. The tempest is the first Category 5 storm to come ashore in the past 15 years.
The hurricane's eye made landfall around 4:30 a.m. near Majahual, a seaport about 40 miles (64 kilometers) notheast of the Mexico-Belize border (see map).
By 8 a.m. the storm had weakened to a Category 3 hurricane, meaning that its winds had dropped to less than 131 miles (211 kilometers) an hour.
The hurricane's powerful winds are expected to cause catastrophic damage as it crosses the peninsula.
Forecasters also predict the storm will dump at least 5 to 10 inches (13 to 25 centimeters) of rain, with some places receiving as much as 20 inches (51 centimeters).
The heavy downpour is expected to cause deadly flash floods and mudslides.
Meteorologist Dennis Feltgen at the National Hurricane Center in Miami said Dean was expected to push a storm surge of 12 to 18 feet (3.6 to 5.5 meters) as it came ashore.
Powerful hurricanes like Dean have very low barometric pressure readings in their eyes. At sea level during calm weather, the normal barometric pressure is about 30 inches (a thousand millibars).
Dean's barometric pressure reading of 26.74 inches (906 millibars) makes it the ninth most powerful hurricane on record in the Atlantic Basin, which includes the Caribbean Sea and the Gulf of Mexico, Feltgen said.
Dean also became the first Category 5 hurricane to make landfall since Hurricane Andrew struck southern Florida in 1992.
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