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Wilma Sets Barometric Pressure Record

October 19, 2005

MIAMI (AP) _ Hurricane Wilma doesn’t stop making history: It is the strongest, most intense Atlantic hurricane in terms of barometric pressure and the most rapidly strengthening on record.

A hurricane hunter plane flying through the Category 5 storm’s eye found a minimum central pressure of 882 millibars, National Hurricane Center forecasters said Wednesday.

That is lower than the 888 millibars recorded in Hurricane Gilbert in 1988. The lowest pressure at landfall on record is 892 millibars in the 1935 Labor Day hurricane in the Florida Keys, which was blamed for more than 400 deaths.

Pressure is often used to compare hurricanes throughout history because there are usually more accurate measurements. Wind gauges are often damaged or destroyed by powerful hurricanes.

Wilma’s top sustained winds were measured early Wednesday at 175 mph, the same as Rita and Katrina when they were at sea and 105 mph faster than the wind speed measured 24 hours before when it was a tropical storm. That wind speed increase is the fastest ever recorded, hurricane meteorologist Hugh Cobb said.

Hurricanes Camille (1969) and Allen (1980) were estimated to have winds of 190 mph, the highest ever recorded, but those readings are suspect because of problems with wind gauges, forecasters said.

A hurricane’s winds are blown because higher-pressure air rushes toward the lower-pressure eye to equalize the difference. Typically, the lower the pressure, the faster the air speeds in. But because the pressure around each storm is different, lower pressure doesn’t always correspond to a specific wind speed.

Wilma dropped from 982 millibars to 882 millibars in 24 hours, or a rate of 4.2 millibars an hour. Gilbert dropped at 3 millibars an hour over 24 hours. Wilma also fell 9.7 millibars an hour over six hours early Wednesday, beating Hurricane Beulah’s drop of 6.3 millibars an hour in six hours in 1967.

The lowest pressure ever recorded in a tropical cyclone was 870 millibars in Typhoon Tip in the northwest Pacific Ocean in 1979.

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On the Net:

http://www.nhc.noaa.gov

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