Helene officially strengthened to hurricane status Wednesday morning, and continues to intensify on its fast and powerful track to a Florida landfall on Thursday.
“Preparations to protect life and property should be rushed to completion,” warned the U.S. National Hurricane Center (NHC) in its Thursday morning update, adding that ‘catastrophic’ winds and storm surge would impact the Northeastern Gulf Coast.
As of Thursday morning, Helene swirled about 560 km southwest of Tampa, Fla., with maximum sustained wind gusts of 150 km/h, maintaining its Category 1 storm strength. It could be a Category 3 major hurricane, with wind gusts between 178–208 km/h when it reaches the Florida Gulf Coast, meaning it will have undergone just 48 hours of rapid intensification over the extremely warm waters of the Gulf of Mexico.
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Hurricane and tropical storm warnings have been issued for parts of Florida and Mexico, as well as a storm surge warning for Tampa Bay and Charlotte Harbor. Residents were urged to heed any evacuation orders as storm surge could rise to life-threatening heights of 6 metres in the Big Bend area of Florida’s Panhandle.
According to the NHC, a significant increase in forward speed is forecast over the next 24 hours, bringing the centre of Helene across the eastern Gulf of Mexico and to the Florida Big Bend coast by Thursday evening or early Friday morning.
“After landfall, Helene is expected to turn northwestward and slow down over the Tennessee Valley on Friday and Saturday,” the NHC says.
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Helene barrels towards Florida, Thursday landfall looming
Landfall is expected along the Florida Panhandle, anywhere from Tampa to Tallahassee, Fla.
According to John Dailey, the mayor of Tallahassee, this could be the strongest storm to ever make a direct hit on the city. Helene could produce “unprecedented damage like nothing we have ever experienced before as a community,” Dailey said in a news conference on Wednesday.
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Thousands have already evacuated, as time is now running out for residents to make appropriate plans for impact. Officials warn that this is not a survivable event for those in coastal or low- lying areas. The threat for flooding rains, damaging winds, and potentially life-threatening storm surge are all on the table. Power outages will likely be counted in the millions of customers.
A state of emergency has been declared for 61 of Florida’s 67 counties. The storm will span beyond Florida, as well, as much of the Southeast prepares for Helene’s exceptionally large and widespread impacts.
“Do not get wedded to the “cone,” as hazards such as tornados, flooding, and storm surge can create dangerous conditions far beyond the cone,” said Florida Gov. Ron DeSantis on X.
Earlier this week DeSantis shared, that there were nearly 18,000 linemen staged, with more on route, ready with search and rescue, and roadway clearing crews.
(The Weather Network’s Mark Robinson will be live on location in Florida as Helene makes landfall)
Life-threatening storm surge
Dangerous storm surge, and strong winds are expected for portions of the Northeastern Gulf Coast, including the Florida Panhandle and sections of Florida’s west coast.
“The combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters moving inland from the shoreline,” says the NHC.
In places like Tampa Bay, where special attention needs to be paid, storm surge could reach between 1.5-2.5 metres, which will cause significant damage if peak heights come to fruition. Florida’s Ochlockonee River could see storm surge as high as 4-5.5 metres, and some isolated areas could even see storm surge up to six metres high.
This is an extreme storm surge forecast, and similar to Hurricane Laura’s surge in Louisiana in 2020. U.S. record-breaking storm surge remains Hurricane Katrina with 8.53 metres (28 feet) across southern Mississippi.
Threat for considerable flash flooding with torrential rains
Total rain accumulations of 100 to 200 mm are forecast over western Cuba and the Cayman Islands, with isolated totals possibly reaching 300 mm. Over the eastern Yucatan Peninsula, 100 to 150 mm rain is expected with isolated totals over 200 mm.
Over the Southeastern U.S., the storm is expected to produce total rain accumulations of 100 to 200 mm of rainfall, and isolated totals of 300 mm. This brings a risk of flooding, some of which could be considerable.
“This rainfall will likely result in catastrophic and potentially life-threatening flash and urban flooding, along with significant river flooding. Numerous landslides are expected in steep terrain across the southern Appalachians,” the NHC warns.
Tennessee’s all-time rainfall record from the tropics is in jeopardy, and currently stands at 345 mm with Tropical Storm Chris in 1982.
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All computer models highlight Hurricane Helene will be well above average in terms of storm diameter, extending to more than 800 km across. It’ll take up roughly half the size of the Gulf of Mexico, with impacts spreading in some cases to as much as 500 km from the eye.
The largest hurricane diameter in history was Typhoon Tip in 1979, having a span exceeding 2,000 kilometres.
Helene is forecast to be about 60 per cent larger than Hurricane Idalia, which caused $3.6 billion worth of damage. Even though Helene is forecast to have a diameter close to 800 kilometres, it’s half of what Hurricane Sandy’s width was in October 2012.
Despite the unexpected lull in activity this hurricane season, remember that we could still see dangerous storms develop over the coming days and weeks. Coastal residents should closely monitor forecasts and have emergency preparedness kits ready to go long before a storm ever threatens land.
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With files from Reuters