"The National Hurricane Center (NHC) has never forecast a depression to become a major hurricane within 60 hours. The entire forecast is substantially faster than any in 36 hours and 48 hours for a tropical depression," said Sam Lillo, a meteorologist and software engineer at DTN Weather.
According to John Cangialosi, one of the NHC's senior hurricane experts, the forecast of Helene's wind speeds of "increasing by 70 knots in 72 hours on September 23 is one of the fastest forecasts" for a potential tropical storm.
"There is a reason to make such a forecast. We are trying to anticipate the possibility of a rapid intensification before it reaches Florida," said Cangialosi.
Hurricane Helene is forecast to make landfall along or near Florida's Big Bend on the evening of September 26 local time with the impact of wind, rain and storm surge across the Southeast, but the path and exact time of landfall may still change. Helene will be the fourth hurricane to hit the United States this year and the fifth to hit Florida since 2022.
Among the computer models used to forecast hurricanes, some show Helene continuing to strengthen and could sharply reduce central pressure to the lowest level ever recorded in the Gulf of Mexico.
The NHC and the National Weather Service often advise residents on a hurricane's path to plan for a higher level than forecast, and Helene is currently forecast to be a Category 3 storm on the 5-point Safir-Simpson hurricane scale when it makes landfall, with winds of 185 km/h. Some models even predict Helene will make landfall as a Category 4 or Category 5 storm.
CNN reported that thousands of people have been forced to evacuate in Florida as Helene is expected to become the strongest storm to hit the US in more than a year.
The storm formed in the northwest Caribbean Sea on the morning of September 24 and rapidly intensified over the extremely warm waters of the Gulf of Mexico.
Flood warnings have been issued for more than 20 million people from Florida to the southern Appalachians. The Big Bend area faces the most serious high tide, which could reach up to 4.5m.
Helene appeared as Florida's Big Bend region is still recovering from some recent storms. Hurricane Debby made landfall in the area in early August as a Category 1 storm and recovery efforts are still underway.
