The Gulf Coast of Florida is bracing for a major storm surge as Hurricane Idalia continues to build strength on its march toward the state’s vulnerable northwestern coastline.
The rush of seawater being bulldozed toward the coast by Idalia, which strengthened into a Category 2 hurricane Tuesday afternoon with winds near 100 mph, is forecast to cause flooding that may be devastating, the National Weather Service is warning, leading to an “extreme life-threatening” situation for anyone who remains in the storm’s path.
With waters predicted to swell up to 15 feet in some spots, battering waves and rising seas are expected to wash away buildings, marinas, docks and piers and discharge a river of dangerous floating debris into the floodwaters. A surge this size would erode beaches, and rip boats away from their moorings, stranding them ashore. Many communities may be uninhabitable for weeks.
“The risk of storm surge across all of the western side of Florida is very real,” said Jill Trepanier, a hurricane climatology expert at Louisiana State University in Baton Rouge. “To me, that’s the biggest threat right now.”
Even though the eye of Idalia is forecast to pass north of Tampa, the upswell of water from the storm’s powerful winds may cause damage in and around the city. The hurricane is expected to intensify Tuesday before making landfall Wednesday morning in the Big Bend region in the northwest portion of the state, potentially as a Category 3 storm.
“Tampa is certainly still in the crosshairs,” said David Zierden, a climatologist at Florida State University. “There’s a tremendous amount of low-lying development and housing and infrastructure in and around Tampa Bay. It’s a significant threat.”
The Tampa area has dodged the full force of other hurricanes in recent years, such as Hurricane Ian last year and Hurricane Charley in 2004, Zierden said, and bearing the full impact of such a large storm surge could be devastating.
Poised to take a direct hit from the hurricane are the Big Bend and Nature Coast regions of Florida north of Tampa. Although not as densely populated as other parts of the state, this area is particularly vulnerable to storm surges. The shallow seafloor and curved coastline act like a basket, collecting the surging waters and funneling them inland.
“If a storm hits an island, for example, a lot of that surge of water can go around,” said Steven Morey, an oceanographer at Florida A&M University. But in Florida’s Big Bend, “the water can pile up without a lot of escape,” he added.
Historically, this stretch of marshy coastline has been lucky, too, having been spared for decades from major hurricanes. But that means many of these communities have not hardened their coastal infrastructure for big storms, Morey said.
“Because this area has not experienced many storms in the past, those communities that do exist along it are not very resilient to this type of storm,” he said.
The areas at highest risk are older communities with structures not built to withstand stronger storm surges, said Mark Luther, an oceanographer at the University of South Florida.
Hurricane experts warned that the wind speeds will probably rapidly intensify Tuesday as the storm passes through the warm waters of the Gulf of Mexico, pushing a wall of water toward low-lying communities.
Trepanier said the conditions are lined up for the storm to worsen into a major hurricane. The storm is passing through a pocket where the wind shear – or choppiness of the atmosphere – is relatively mild, which helps hurricanes cohere and organize, she said. Plus the warm waters can add to a storm’s strength.
“There is no lack of warm water anywhere in the Gulf of Mexico,” she said. “It’s exceptionally hot. The heat potential is there.”
The storm is rotating counterclockwise around the eye, and communities to the right, or south, of the oncoming storm may also be particularly vulnerable for flooding, experts said. That’s where the momentum of the storm is pushing wind and water onshore.
“The winds are moving that water onshore in that quadrant and essentially piling it up,” said Thomas Frazer, dean of the University of South Florida College of Marine Science. “Because Florida has such a low elevation, there’s a lot of room for that water to move onshore.”
The tides from an approaching super blue moon are also a big factor. One of the biggest tides of the year is expected Wednesday afternoon, potentially coinciding with the storm surge, Frazer added.
“Everybody should be on guard for this one,” said Frazer, who was moving his boat Tuesday morning to a safer area.
Luther, the University of South Florida oceanographer, spent the days before the storm moving two vintage vehicles to high ground and loading up another car with some of his wine collection. In case of minor flooding, he took items off the floor of his St. Petersburg home, he said in a phone interview while driving to a hotel to ride out the storm.
If there is major flooding, he said, “all bets are off.”
(c) 2023, The Washington Post · Dino Grandoni, Joshua Partlow
