UPDATE: Wilma “A Catastrophic Category Five Hurricane;” Lowest Pressure Ever Recorded

October 19, 2005

Hurricane Wilma, the 12th of the season, has become “a catastrophic category five hurricane on the Saffir-Simpson scale” states the latest bulletin from Miami’s National Hurricane Center. In less than 24 hours Wilma, which the NHC described as a Category 1 hurricane on the Saffir-Simpson scale at noon EDT yesterday, has strengthened to a Category 5 storm. Maximum sustained winds are near 175 mph (280 km/hr) with higher gusts.

The most recent NHC bulletin – issued at 5 a.m. EDT – noted that Air Force reconnaissance planes had recorded a minimum central pressure of 884 Mb (26.10 inches) – “the lowest minimum pressure ever measured in a hurricane in the Atlantic basin.” 17 hours ago, at noon yesterday, it was 977 Mb. The NHC did indicate that “this value should be used with caution until calibrated.”

Only one other hurricane, the unnamed storm that struck the Florida Keys in 1935, has ever registered an atmospheric pressure below 900 millibars.* It was recorded at 892 Mb. Andrew’s minimum atmospheric pressure was 922 Mb.

Wilma is not as large as Katrina and Rita. The NHC said: “Hurricane force winds extend outward up to 15 miles (30 kms) from the center and tropical storm force winds extend outward up to 160 miles (260 kms).” It could still be quite deadly. Andrew was also a comparatively small hurricane.

“All interests in the Florida Keys and the Florida Peninsula should closely monitor the progress of Wilma, ” said the NHC. The latest bulletin said the hurricane’s center was located “near latitude 17.2 north-longitude 82.5 west or about 170 miles (270 kms) south-southwest of Grand Cayman and about 365 miles (590 kms) southeast of Cozumel, Mexico.”

A hurricane watch is in effect for the east coast of the Yucatan Peninsula from Cabo Catoche to Punta Gruesa. A hurricane watch also remains in effect in Cuba for the provinces of Matanzas westward through Pinar del Rio…and for the Isle of Youth. A tropical storm warning remains in effect for Honduras from the Honduras/Nicaragua border westward to Cabo Camaron. A tropical storm warning and a hurricane watch remain in effect for the Cayman Islands.

Wilma is moving toward the west-northwest near 8 mph (13 km/hr). The NHC expects a turn toward the northwest during the next 24 hours. Heavy rains of between 10 and 15 inches (16 to 25 cms) are predicted along the entire storm front, “with local amounts near 25 inches (39 cms) in mountainous terrain across Cuba through Friday.”

The NHC also said: “Additional rainfall accumulations of 5 to 10 inches (8 to 16 cms) with local amounts of 15 inches (25 cms) are possible across the Cayman Islands, Swan Island and Jamaica through Thursday. Storm total additional rainfall accumulations of 5 to 10 inches (8 to 16 cms) with local accumulations of 4 to 6 inches (6.4 to 9.6 cms) with isolated amounts of 8 to 12 inches (12.8 to 19.2 cms) are possible from Honduras northward to the Yucatan Peninsula of Mexico through Thursday.

* An alert reader has pointed out that the minimum pressure of Hurricane Gilbert was measured at 888 Mb, but it rose prior to landfall.

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