As of 8 p.m., Hermine’s maximum sustained winds had increased to 80 mph and the storm was still strengthening. In less than 36 hours, the storm had intensified from a tropical depression with 35 mph winds to a hurricane whose winds could come close to 90 mph before landfall. Intensifying storms tend to inflict more damage at landfall than those that are weakening.
Florida has not experienced hurricane conditions since 2005 during Hurricane Wilma. In fact, the entire Gulf of Mexico hadn’t had a hurricane since Ingrid in 2013 – a period of almost three years – the longest on record.
A hurricane warning is in effect for a large portion of Florida’s Big Bend, which connects the panhandle and peninsula, from the Suwannee River to Mexico Beach along the Gulf Coast. The center of Hermine could make landfall anywhere between those locations around midnight. A dangerous storm surge is possible as the storm rolls ashore on Thursday night — particularly on the south side of the storm — and flooding will be exacerbated by heavy rain.
A storm surge warning is in effect from Franklin County through Hernando County. The highest surges are expected in coastal Wakulla, Jefferson and Taylor counties, and could reach 6 to 7 feet in the most vulnerable locations.
The timing of the tides will determine which locations get the worst impacts from storm surge.
Unlike Sandy in 2012, which arrived precisely at one of the highest astronomical tides of the year, Hermine should make landfall near low tide in Apalachicola, Fla., which reduces the net water level by about 1.2 feet. But in Cedar Key, roughly 150 miles farther down the coast, the storm is expected to make landfall closer to high tide when the water level is about 3.2 feet higher than at low tide.
Some of Apalachicola’s worst storm surge events include Hurricane Dennis in 2005 and Hurricane Elena in 1985, and Hermine’s surge could rival the surge produced by Category 3 Hurricane Dennis, which hit near Pensacola.
Another major threat facing north Florida and the Southeast United States in the coming hours and days is inland flooding caused by excessive rainfall. Through Sunday morning, a vast swath of the Big Bend and panhandle will get over six inches of rain. Some isolated areas could see more than 10 inches, especially where heavy rain bands form.
After passing over Florida, Hermine will track along the East Coast, bringing heavy rain to Georgia and the Carolinas. How far inland the storm tracks is still a question mark until the center passes through Florida and back over water in the Atlantic.
All landfalling tropical cyclones bring with them the risk of tornadoes. Hermine is no exception, and there is an elevated threat of tornadoes from the central Florida peninsula up into southeastern Georgia Thursday and Thursday night, including much of the Florida Panhandle. Tropical cyclone-induced tornadoes are generally not on the high end of the scale, but even EF-0 and EF-1 tornadoes are capable of causing damage to homes and trees.
Florida has not experienced hurricane conditions since Oct. 24, 2005, when Wilma hit near Naples as a Category 3 storm. As of Thursday, that is 3,965 days (10.9 years), a span that is nearly 1,800 days (4.9 years) longer than the previous “hurricane drought.” Note that the long-term average return period is just 507 days (1.4 years), or roughly five every seven years.