Hurricane Wilma Is Most Powerful Storm in Atlantic History

Willie Drye
for National Geographic News

October 19, 2005

The 2005 hurricane season reached two more milestones this week:
Hurricane Wilma has become the 21st tropical storm of the season and
has quickly grown into the most powerful hurricane on record in the
Atlantic Basin.

The storm is expected to make landfall in the U.S. late Saturday on the southwest coast of Florida. Evacuation orders have been issued for Monroe County, which includes the Florida Keys.

State parks in the Keys have been closed to encourage tourists to leave the islands, and an evacuation order for residents goes into effect tomorrow.

Also, patients in Keys hospitals are being airlifted out of the islands.

Record-Breaker

One of the best indicators of a hurricane's intensity is its barometric pressure; very powerful hurricanes have very low readings. As of 11 a.m. Eastern time today Wilma's barometric pressure reading had dropped to 26.04 inches or 882 millibars, a record low.

Forecasters expect Wilma to lose some of its intensity before landfall, but the storm is still expected to come ashore as a major hurricane, with winds of at least 111 miles an hour (180 kilometers an hour).

The previous record for the Atlantic Basin was Hurricane Gilbert in 1988, which had a low pressure of 26.18 inches or 888 millibars. Gilbert made landfall at Mexico's Yucatán Peninsula.

The most intense hurricane to make landfall in the U.S. was the Labor Day hurricane of 1935, which had a reading of 26.35 inches or 892 millibars, when it struck the Florida Keys.

Wilma began on October 15 as a tropical depression in the central Caribbean Sea. When it became a tropical storm two days later, it was the 21st of the season. The last time that many tropical storms formed in a single season was 1933.

Wilma has astonished meteorologists with its rapid intensification. As of 4 p.m. Tuesday, Wilma was a minimal hurricane with winds of 80 miles an hour (130 kilometers an hour). But only 18 hours later it had mushroomed into the Atlantic's most powerful storm.

James Franklin, a hurricane specialist at the National Hurricane Center in Miami, said Wilma "obliterated … by a wide margin" the previous record for rapid intensification set in 1967.

"It's certainly the most dramatic strengthening I've ever seen," said Keith Blackwell, hurricane researcher at the University of South Alabama's Coastal Weather Research Center in Mobile.

Blackwell said Wilma's rapid intensification was caused by the warm waters of the northwest Caribbean, which have spawned other extremely powerful storms. Hurricane Wilma formed in the same area as Hurricane Mitch did in October 1998.

Storm-Weary Gulf Coast

Hurricane Wilma became only the latest unusual event in a season full of anomalies.

Two hurricanes that formed in July—Dennis and Emily—were the most intense on record for that month.

In August, Hurricane Katrina virtually destroyed New Orleans and the Gulf Coast. Less than a month later Hurricane Rita became the third most powerful hurricane ever to form in the Atlantic before weakening and making landfall near the Texas-Louisiana border.

"There are so many astounding things about this season," Blackwell said.

In Florida, which was pounded by four intense hurricanes last summer, residents are becoming weary of the storms.

"Montana looks really good to me right now," joked Irene Toner, a director of the Monroe County Emergency Management Department.

Toner has had to order repeated evacuations of the low-lying islands, which are very vulnerable to hurricanes.

"We were on guard really since the last hurricane season," Toner said. "We were surprised that this season has been as busy as it has, but we were not overly shocked by that."

The hurricane season continues until November 30.

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

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