Post-tropical cyclone Isaias pushed inland across the US Gulf Coast on Monday, and forecasters warned that the danger is far from over as flash flooding and damaging winds spread deeper into the Southeast.
The US National Hurricane Center (NHC) said Isaias was moving over southern Alabama and that the threat zone had expanded farther inland. The storm was located about 88.5km south-southwest of Montgomery, Alabama, packing maximum sustained winds of 100km/h, the agency reported.
While Isaias is expected to continue weakening, the NHC said it will keep generating strong, gusty winds well away from the coast before dropping below gale force later.
Earlier, Isaias slammed into the US Gulf Coast with heavy rain and powerful winds as it came ashore in northwestern Florida, the NHC said.
“Isaias makes landfall near Destin, Florida,” the center said in an earlier bulletin.
“Life threatening storm surge impacting Gulf Coast as dangerous hurricane conditions and flash flooding spread inland,” it added before downgrading the system to a post-tropical cyclone.
The NHC said Isaias rapidly shed strength, weakening into a Category One event after making landfall near Destin and then deteriorating further into a post-tropical cyclone. Even so, officials cautioned that storm surge and flooding remained serious risks as power infrastructure failed in places.
Florida’s emergency services urged residents to shelter in place and stay alert for hurricane conditions across the north of the state after Isaias first came ashore as a Category Two storm.
Along the coastline, mandatory evacuation orders emptied some communities and businesses were boarded up as Isaias became the first hurricane of an Atlantic season that began in June, a season dampened by a historic El Niño pattern that typically shifts major storm activity toward the Pacific.
In Pensacola, about 80 kilometres west of Destin, winds were reported tearing roofs off some homes and businesses, snapping tree limbs, and knocking out electricity.
Debris on an intersection as wind and rain from Hurricane Isaias pass through Pensacola in Florida
“Things are flying really fast and I’ve never seen wind this fast before, so it’s intense, it’s scary,” Jonathan Ramos, a 40-year-old government employee, said at his hotel in Pensacola, where the power went out.
“I don’t recommend people coming down here for fun to do this,” he added.
As the storm struck shore, nearly 380,000 customers in Florida and more than 210,000 in Alabama were without electricity, according to Poweroutage.us.
Before the worst conditions arrived, caravans of repair trucks moved through Pensacola and Navarre toward staging areas in anticipation of widespread outages, reporters on the scene said.
Water service to buildings was suspended.
Fueled by record-warm Gulf waters heated by climate change, Isaias intensified rapidly and became the first hurricane to hit the US mainland since Milton in 2024.
Florida Governor Ron DeSantis told a press briefing that “we’ve got a massive amount of supplies and personnel ready to respond once the storm hits”.
US President Donald Trump cancelled his visit to a college football game between the University of Georgia and the University of Alabama in Tuscaloosa, Alabama, because of the hurricane.
Mandatory evacuation orders were issued in several Florida counties, though officials said impacts could be felt across a broad swathe of the southeastern United States.
Storm surge, arriving on top of high tide, was expected to inundate areas that are usually dry, with the NHC warning waters could climb as high as 2.7m near the Alabama-Florida border.
Forecasters also warned that intense rainfall could set off flash floods and force rivers to spill over their banks.
Two airports in northwestern Florida have suspended operations.
A man puts shutters on his home before the arrival of Hurricane Isaias in Pensacola, Florida
Meteorologists said Isaias’s late-season emergence was largely tied to an El Niño of historic strength.
El Niño, the warm phase of the El Niño -Southern Oscillation (ENSO), can generate strong vertical wind shear over the Atlantic — a hostile environment that often rips developing storms apart.
“We have been seeing basically nearly record strong shear throughout the Atlantic Basin this year and that is consistent with what we’d expect to see with a strong El Niño event,” Michael Fischer, of University of Miami’s Rosenstiel School of Marine, Atmospheric and Earth Science, said.
In the Pacific, the dynamics tend to reverse, with reduced shear enabling storms to organize and strengthen.
The Pacific has already produced several hurricanes this year, some reaching Category Five intensity.
“Sea surface temperatures in the Gulf of Mexico are in record territory because of fossil fuel-driven climate change,” Marc Alessi, a climate scientist with the Union of Concerned Scientists, said.
“Isaias was able to tap into all of that energy in the ocean to develop into a major hurricane,” he added.
According to an analysis by nonprofit Climate Central, Gulf of Mexico waters are about 1.4C above the pre-industrial average, and Isaias “formed over waters that were 600 times more likely to be that temperature because of climate change”, Kristina Dahl, the group’s vice president for science, said.
Ms Dahl added that storm surge can be amplified because climate change has raised sea levels by around 16cm in the region, meaning surging water builds on a higher baseline.
Scientists also link heavier hurricane rainfall to warming, since a hotter ocean and atmosphere can hold and transport more moisture.
Isaias also disrupted offshore energy production in the Gulf of Mexico, prompting evacuations of platforms and rigs.
About 71% of the region’s oil output was temporarily shut in — nearly 1.5 million barrels a day taken off the market — according to the Marine Minerals Administration.
About 59% of gas production was also suspended.
