Rita Now Third Most Powerful Hurricane in Atlantic History

Willie Drye
for National Geographic News
September 22, 2005
Fueled by the warm late-summer waters of the Gulf of Mexico, Hurricane
Rita exploded overnight into the third-most powerful hurricane on record
for the Atlantic Basin.

As of 5 a.m. today the hurricane's strongest winds were blowing at 175 miles an hour (280 kilometers an hour) and the barometric pressure at the storm's center had fallen to 26.51 inches, or 897 millibars.

Since the invention of the barometer in the 17th century, a hurricane's lowest barometric pressure reading has become a standardized way for meteorologists to measure a storm's intensity.

As a hurricane gains strength, its barometric pressure reading drops. A normal barometric pressure reading at sea level during calm weather is roughly 30 inches, or 1,000 millibars.

The lowest barometric pressure reading recorded in the Atlantic Basin was Hurricane Gilbert in 1988, with a reading of 26.18 inches, or 888 millibars. Gilbert struck Mexico's Yucatán Peninsula. The second-lowest reading on record was 26.35 inches, or 892 millibars, during the Labor Day hurricane of 1935. That hurricane struck the Florida Keys.

Residents Flee Gulf Coast

More than a million people on the hurricane-battered Gulf Coast are moving inland today to escape Rita's ferocious winds.

"Traffic is horrible now," said Robert Arnold, a resident of the Houston suburb of Sharpstown. "People are gridlocked, pulled over on the side of the road. People are running out of gasoline. It's very difficult to get gasoline."

Hurricane Rita is the fifth powerful hurricane to strike the Gulf Coast since August 2004 and the second Gulf hurricane in less than a month to reach Category Five status on the Saffir-Simpson scale.

Hurricane Katrina reached Category Five status shortly before it weakened and struck southeastern Louisiana on August 29 with winds of more than 140 miles an hour (225 kilometers an hour). Katrina's storm surge caused devastating flooding in New Orleans, and the hurricane inflicted massive damage in Mississippi.

The series of powerful Gulf Coast storms started with Hurricane Charley, which made landfall at Punta Gorda on the west coast of the Florida peninsula in August 2004.

"When hurricanes get into the Gulf, they're going to hit something," said Gary Beeler, a meteorologist at the National Weather Service office in Mobile, Alabama.

Hurricane Rita is expected to make landfall at or near Texas's Galveston Bay late Friday or early Saturday. Forecasters think Hurricane Rita will weaken some before it comes ashore, but will still arrive with winds of at least 130 miles an hour (210 kilometers an hour) and inflict massive damage.

"It's the difference between tremendous damage and devastating damage," Beeler said. "It'll still be very bad. Texas hasn't been hit by something this strong in quite a while."

Like all of the recent powerful Gulf of Mexico hurricanes, Hurricane Rita underwent a period of rapid intensification. The storm climbed from a Category Two to a Category Five hurricane in less than 24 hours.

A Category Two hurricane has winds of 96 to 110 miles an hour (155 to 177 kilometers an hour). A Category Five hurricane has winds exceeding 155 miles an hour (250 kilometers an hour).

Hurricane Rita's rate of intensification approaches the most rapid intensification on record for any tropical cyclone. In 1983 a typhoon in the Pacific Ocean underwent an intensification that boosted its top winds from 75 miles an hour (120 kilometers an hour) to 173 miles an hour (278 kilometers an hour) in less than 24 hours.

Beeler said the warm waters of the Gulf of Mexico have fueled the recent spate of monster hurricanes.

"For the last few years, the Gulf has had very warm waters," Beeler said. "That doesn't cause hurricanes to develop, but it acts like a high-octane fuel for them."

Rita's Birth

Rita began as a tropical depression just east of the Bahamas on September 18. The storm moved through the Straits of Florida as a Category One hurricane and then started strengthening as it moved west of Key West and into the Gulf.

Beeler said Rita might have rapidly intensified because it crossed paths with an eddy of deep, warm water. Such drifting eddies often form in the Gulf of Mexico in the late summer.

"When it stirs up the water, it stirs up more fuel instead of cooler water," Beeler said.

Hurricane Rita's intensification also was aided by the fact that there are no upper-level winds—known as wind shear—to tear the storm apart or hinder its development, Beeler said.

Hurricane Rita is the 17th tropical storm of the active 2005 season and the 9th hurricane. Meteorologists think this summer's activity is a continuation of a decade-long cycle of busy hurricane seasons.

Many meteorologists think ocean currents that cause fluctuations in the salt content of waters are causing the recent active seasons. When the salt content is higher—as is the case in the Atlantic—the water is warmer and more hurricanes form.

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

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