A Late Weakening Dampened Hurricane Irma’s Power, But It Still Set Plenty of Records

Before crashing into Florida, Hurricane Irma set all sorts of records for brute strength as it flattened Caribbean islands and swamped the Florida Keys. Irma’s assault — so soon after Harvey’s deluge of Houston — marked the first time the U.S. was hit by two Category 4 storms in the same year.

Irma hit the Sunshine State as a big wide beast, though not quite the monster it once was shaping up to be. Earlier, it was the most powerful recorded storm in the open Atlantic. But as the once-Category 5 storm neared the U.S. mainland, it lost some oomph after running into the northern coast of Cuba.

Winds dropped to a quite potent 115 mph (185 kph) by the time Irma made landfall on Marco Island, on the Florida peninsula, still a major and dangerous hurricane yet not near its 185 mph (297 kph) former self when it set a record Tuesday for the most powerful storm in the open Atlantic.

Florida can thank Cuba, where it did hit as a Category 5 storm, said Maue and Jeff Masters, meteorology director for Weather Underground.

Irma would probably have hit Florida as a Category 5 hurricane if it had missed Cuba, Masters told The Associated Press.

Masters predicts that when Irma is done it will go down as one of the five costliest hurricanes in U.S. history, but not up with the top three of 2005’s Hurricane Katrina, 2012’s Sandy and this year’s Harvey. Still, he guessed, it will be grouped with two other South Florida storms: 1992’s Andrew and 2005’s Wilma.

Irma’s two U.S. landfalls were unusually powerful. When Irma passed over the Florida Keys Sunday morning its central pressure was the seventh lowest for a smack into the United States. Only the 1935 Labor Day storm, 1969’s Camille, Katrina, Andrew, an 1886 Indianola, Texas, storm, and a 1919 Florida Keys storm were more intense based on atmospheric pressure. Irma ties the killer 1928 Lake Okeechobee hurricane.

Irma’s second landfall on Marco Island, taken by itself, still would rank among the top couple dozen landfalls in intensity, slightly weaker than Harvey.

Irma set plenty of records, according to a two-page list compiled by Colorado State University researcher Phil Klotzbach:

-Its 185 mph (297 kph) winds were the highest on record for the open Atlantic ocean, outside the Gulf of Mexico and Caribbean sea. Only one other storm in the entire Atlantic basin — 1980’s Allen — was stronger.
-It spent three consecutive days as a top-of-the-scale Category 5 hurricane, the longest in the satellite era.
-It generated the second most Accumulated Cyclone Energy — a key measurement that combines strength and duration — in the satellite era. Irma generated about as much as energy as entire normal Atlantic hurricane season.
-It was the strongest storm to hit the Leeward Islands.
-It’s the first Category 5 hurricane to hit Cuba, which regularly gets assaulted by hurricanes, in nearly 100 years.

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