The National Weather Service’s first official look at Hurricane Irma confirms what forecasters had feared: hurricane-strength winds in parts of Miami-Dade and a significant storm surge that battered Florida’s southwest coast.
Near tony Fisher Island and at the Fowey Rocks lighthouse just east of Biscayne Bay, sustained winds reached 74 mph and 81 mph, just meeting the threshold for a Category 1 hurricane, the office said in a Friday report. In Collier County, where Irma made a second landfall on Marco Island after crossing Cudjoe Key Sunday morning, sustained winds reached 93 mph.
Storm surge was slightly lower than expected but still significant: six to eight feet of water flooded the tiny fishing village of Chokoloskee near the shoreline, with three to five feet sweeping across the entire island.
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Meteorologists are still reviewing data and have not confirmed flooding levels in South Florida, although they noted peak tide readings in downtown Miami and Key Biscayne: 2 feet in Miami and 3.23 feet on the island.
While an official report is still being compiled by various agencies, the report for the first time confirms hurricane conditions around Miami, even if those winds have so far only appeared in two locations. Some stations also failed when conditions got severe, so peak winds may have been missed.
“When you have gusts and bursts of wind that can last a few seconds and you have several of those and they’re continuously going above 74 mph, to me those are hurricane conditions even if they don’t technically fall under that category,” said Warning Coordination Meteorologist Robert Molleda. “For all intents and purposes, Southeast Florida had Category 1 conditions.”
The data represents a vast trove of records clocked by wind and tidal gauges around the state that the National Weather Service will comb through in the coming days to confirm reports, said meteorologist Tony Reynes. As numbers are confirmed, the report will be updated, he said.
The numbers also have to be analyzed by the National Hurricane Center, which puts together a more comprehensive post-storm report. The two hurricane-force wind recordings in Government Cut and the Fowey lighthouse, for example, were at elevations higher than what’s normally considered surface readings, Molleda said.
“So there’s more to this data than meets the eye,” he said.
To confirm data, the weather service sends out teams of surveyors to compare damage with readings from instruments. If a gauge records strong winds but no damage is apparent, they do more investigating or disregard it, Reynes said. They also look at the reliability of equipment. Reports from airport instruments, maintained by the Federal Aviation Authority, are almost always reliable, he said.
In the hours leading up to Irma, National Hurricane Center forecasters had warned that Florida’s Gulf Coast, from Cape Sable to Captiva, could get hammered with a 10- to 15-foot surge from the monster storm. Hurricane winds extended 80 miles from Irma’s center, nearly blanketing the state. They also warned that despite the storm shifting to the west with a track moving up the Gulf Coast, Southeast Florida could still see three to five feet of water come ashore.
Inland around South Florida, sustained winds were slower but peak gusts remained fierce. At Opa Locka Airport, top sustained winds reached 64 mph with gusts reaching 111 mph at about 7 p.m. Sept. 10. Miami International Airport recorded sustained winds of 52 mph with gusts of 95 mph about 1 p.m., while Fort Lauderdale-Hollywood International Airport had 52 mph sustained winds and peak gusts of 91.5 mph. At the North Perry Airport in Hollywood, sustained winds reached 56 mph with a top gust of 102 mph.
On the west coast, sustained winds at Naples Municipal Airport reached 93 mph at 4 p.m., just after Irma made landfall to the south on Marco Island, with a top gust of 107 mph.
While hurricane-force winds in Miami have so far only been confirmed in two locations, the frequency and abundance of such high wind gusts make it clear that much of South Florida was battered by hurricane conditions, said Molleda.
The Weather Service also confirmed that two tornadoes touched down on the evening of Sept. 9, with one in coastal Broward near Wilton Manors and a second in Homestead near the Homestead-Miami Speedway.
An earlier version of this story incorrectly reported peak wind gusts recorded at South Florida airports.
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