$202b worth of damage dodged as Irma's eye shifts 32km

Boats wrecked by Hurricane Irma are seen from a plane in Sint Maarten, Netherlands on Sept 11, 2017.
Boats wrecked by Hurricane Irma are seen from a plane in Sint Maarten, Netherlands on Sept 11, 2017. PHOTO: REUTERS

MIAMI • Thirty-two kilometres may have made a US$150 billion (S$202 billion) difference.

Estimates for the damage Hurricane Irma would inflict on Florida kept mounting as it made its devastating sweep across the Caribbean. It was poised to be the costliest US storm on record. Then something called the Bermuda High intervened and tripped it up.

"We got very lucky," said Mr Jeff Masters, co-founder of Weather Underground in Ann Arbor, Michigan.

If Irma had passed 32km west of Marco Island instead of striking it on Sunday, "the damage would have been astronomical".

A track like that would have placed the powerful, eastern eye wall of Irma on Florida's Gulf Coast. By one estimate, the total cost of the damage fell to about US$50 billion on Monday from US$200 billion over the weekend.

The state escaped the worst because Irma's powerful eye shifted west, away from the biggest population centre of sprawling Miami- Dade County.

The credit goes to the Bermuda High, which acts like a sort of traffic cop for the tropical North Atlantic Ocean. The circular system hovering over Bermuda jostled Irma onto northern Cuba last Saturday, where being over land sapped it of some power, and then around the tip of the Florida peninsula, cutting down on storm surge damage on both coasts of the state.

"The Bermuda High is finite and it has an edge, which was right over Key West," Mr Masters said.

Irma caught the edge and turned north. For 10 days, computer-forecast models had struggled with how the high was going to push Irma around and when it was going to stop, said Mr Peter Sousounis, director of meteorology at AIR Worldwide. "I was very surprised not by how one model was going back and forth - but by how all the models were going back and forth."

In the end, Irma hit the Florida Keys as a Category 4 hurricane with 209kph winds, then as a Category 3 on Marco Island. It reached the Tampa Bay area as a Category 2.

By contrast, Hurricane Andrew in 1992 ploughed into the east side of Florida as a Category 5.

"With Irma, little wobbles made a huge difference," said disaster modeller Chuck Watson.

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A version of this article appeared in the print edition of The Straits Times on September 13, 2017, with the headline '$202b worth of damage dodged as Irma's eye shifts 32km'. Print Edition | Subscribe