Hurricane Irma quirk averted worst-case-scenario for storm surge

The U.S. Geological Survey will be collecting this week special storm surge devices it placed throughout the state before Irma made landfall Sunday.

But by all accounts, the surge was not as fierce as the up to 15-feet worst-case-scenario predicted over parts of the southwest coast.

While the Keys got wiped clean in some places, the counterclockwise swirl of Irm’a winds promised flooding of greater proportions over areas south of Naples north to Fort Myers and up the Caloosahatchee River.

In the end, it was Jacksonville that had the highest water levels.

A minor jog inland, seen on hurricane center track forecasts Sunday afternoon, sent surge into Naples and Everglades City, but complete devastation was averted.

Related: Full coverage of Irma’s aftermath.

Here’s how two things kept Florida from seeing worse from Irma:

From the very first stirrings of rising air and budding thunderstorms off the coast of Africa, Hurricane Irma had a red carpet through the tropical Atlantic, an atmospheric buffet table of warm seawater and light shear to nourish its growth.

Satellite image of 93L, which would become Irma, taken 3:45 a.m. EDT Aug. 30, 2017.

Its explosion from a tropical storm Aug. 30 to a Category 3 hurricane the next day was one for the record books. By Sept. 5, Irma was a violent Category 5 tropical cyclone with 185 mph winds — a power it would hold for a whopping 37 consecutive hours.

Irma decimated the northern Leeward Islands, raking over Barbuda and the Virgin Islands before setting on a furious path toward Florida.

But when the vulnerable peninsula faced worst-case scenarios that buzzed the powerful storm first up one side then the other, Mother Nature stepped in to tweak Irma’s plan.

By the grace of Cuba’s northern coast, which was abraded by Irma before the strong Cat 4 hurricane reached the Florida Strait , and a tongue of dry air sucked into its massive, state-swallowing wind field, the storm weakened slightly and couldn’t regain strength before making its first landfall Sunday morning at Cudjoe Key.

Hurricane Irma made landfall on Cudjoe Key at 9:10 a.m. Sunday, Sept. 10, 2017.

A subtle wiggle west that made Marco Island its second landfall target kept the deepest and deadliest storm surge away from Naples, Fort Myers and Tampa as fewer of the counterclockwise lashing winds were over the Gulf of Mexico.

“There are just so many little subtle things that can make all the difference,” said Jonathan Erdman, a senior digital meteorologist at Weather.com. “After it hit the Keys, it took a more due north path instead of north-northwest, and that drove the eyewall ashore near Marco Island, which started weakening it.”

At the same time, however, that western wobble put the east coast metro areas within closer reach of Irma’s 80-mile hurricane wind-span and 220-mile stretch of tropical storm-force winds. It also meant more flooding in Jacksonville, which suffered inundation from Irma’s southeast squall.

“It’s not over yet,” said Colorado State University hurricane researcher Phil Klotzbach, noting the flooding in Jacksonville and potential impact in Georgia. “We’re going to learn a lot from this storm, and it certainly could have been worse.”

In Palm Beach County, gusts of 91 mph were recorded at Palm Beach International Airport on Sunday evening as the most potent part of Irma blew through. Other preliminary high wind gusts include 79 mph in Boca Raton, 90 mph in Lake Worth, 84 mph in Juno Beach, 77 mph in Jupiter, 71 mph in Pahokee, 67 mph in Boynton Beach, 65 mph in Belle Glade, 56 mph in Delray Beach and 55 mph in Greenacres.

Massive black olive trees toppled by Hurricane Irma block South Olive in West Palm Beach on Monday. Sept. 11, 2017

“I think Floridians have had a good display of how if you are on the east side of a hurricane, you can be much worse off than on the west side,” said Dan Kottlowski, a hurricane expert at AccuWeather. “Hurricane Matthew passed about the same distance away from you that Irma did, but Matthew was to the east.”

The highest wind gust in Palm Beach County from 2016 Hurricane Matthew was estimated at 67 mph in Juno Beach.

Throughout the county, Irma’s gusty winds, along with sustained speeds of 58 mph at Palm Beach International Airport, uprooted trees, tore street lights from their perches, ripped signs from the ground, shredded shrubbery and cracked palm trees in half.

Kaylie Atteo of West Palm Beach was shocked to find five towering shade trees on South Olive Avenue stretched across the road, their roots lifting up sidewalks as Irma’s winds caught their canopies and took them down.

The intracoastal waterway splashes over the sea wall in West Palm Beach as Hurricane Irma moves through Florida, September 10, 2017. (Greg Lovett / The Palm Beach Post)

“I wrapped up my furniture and put it up on blocks because we just didn’t know what to expect,” said Atteo. “But I never thought these trees would go down because the storm went so far west.”

Atteo spent the night in Boynton Beach with her mother, but Steven Smilack, whose home is next to one of the massive downed trees, stayed. With shutters on his two-story home, he said he never heard the trees go over and didn’t know they had fallen until this morning.

“We just came out and saw what you are seeing,” he said.

By Monday morning, Irma was downgraded to a tropical storm and then a depression.

kmiller@pbpost.com Twitter: @kmillerweather

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