The once powerful Florence took a hit Thursday, but its life as a major hurricane is likely not over just yet, and it has East Coast residents on the edge of their seats.
The tropical storm is predicted to re-intensify to a Category 3 hurricane by Monday and odds have increased that it will have direct effects on the East Coast starting between Wednesday and Friday next week, anywhere between Florida and southern New England.
At 11 a.m. on Friday, Tropical Storm Florence was centered about 1,800 miles due east of Miami and tracking toward the west at 8 mph. It has peak sustained winds of 65 mph. “Florence’s weakening appears to have stopped,” the National Hurricane Center wrote in its advisory.
Florence wilted Thursday as it plowed into the subtropical jet stream. The strong wind shear disrupted the thunderstorms at its core and caused the storm’s peak winds to fall from 130 mph to 70 mph in just 30 hours.
So how could that be bad for the East Coast? Weaker storms are steered by different layers of the atmosphere than stronger storms. A weak storm is steered more by a shallow low-to-mid-level layer of the atmosphere, while a strong storm is steered by a deep layer of the atmosphere. As soon as Florence’s structure fell apart Thursday, it turned westward with the low-level trade winds.
Although a direct hit is not inevitable, odds have increased that this storm may have a hard time finding an escape route as it draws closer to the East Coast. There is still a chance the storm could slow down as it nears the U.S. and meander offshore before turning back out to sea. But it’s not a big chance.
When you combine the 70 members from the American and European modeling systems, about 70 percent of them make landfall along the East Coast.
The primary simulation of the European model has demonstrated remarkable consistency with a hurricane landfall in the Mid-Atlantic on the past five runs, dating back to Tuesday night.
Significantly, the average track of the American model simulations, which had suggested the storm was most likely to stay well out to sea, has trended closer to the coastline with time. The average European model simulation has shifted its track from just off the Mid-Atlantic coast to onshore. In sum, both models are increasingly threatening.
Assuming the storm does come ashore, it is still too soon to know exactly where. The European model has favored the Mid-Atlantic, but small changes in the storm’s path could place the Southeast or Northeast coasts in the line of fire.
Because of the uncertainty in the storm’s final destination, it is premature to discuss exactly what hazards it will inflict, where, and when. But it is reasonably likely some coastal areas will deal with a damaging wind threat, flooding rain, and a substantial storm surge – which is a rise in ocean water above normally dry land. Some areas further inland could also contend with damaging winds and flooding rain.
Even if Florence avoids a direct hit on the East Coast, it will likely come very close, resulting in dangerous surf, beach erosion, and the potential for coastal flooding.
Despite weakening on Wednesday, Florence has already started to rebound as the wind shear relaxes. From Saturday onward, Florence will be over the warmest ocean it has been since it formed eight days ago, which is fuel for hurricanes.
A pool of anomalously warm water over the western Atlantic will provide ample fuel for another round of intensification. By next Tuesday, the National Hurricane Center predicts Florence will be on the brink of Category 4 intensity with 130 mph sustained winds.
If Florence does hit or make it close to the East Coast, it would be a first for a storm in this location. No tropical storm or hurricane has ever gotten close to the United States when it was anywhere near Florence’s position.
But the unusually strong high pressure system that is predicted to park itself north of the storm seems like it has the potential to push Florence on an unprecedented and potentially perilous course.
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Now is the time to beginning thinking about hurricane preparedness if you live along or near the coast.
Do you have a plan if the storm targets your area? Do you know where you would go if evacuations are required? Do you have an emergency kit with at least three days’ worth of critical supplies? Do you have trees that could fall on your house during a windstorm? Trim them now. Declutter drains and gutters.
Elsewhere, two tropical waves in the far eastern Atlantic have a high probability of becoming a tropical storm or hurricane. The westernmost wave is the one to most closely monitor, as models keep it at low latitudes, potentially reaching the Lesser Antilles by Thursday. If these disturbance become tropical storms, they will be named Helene and Isaac.
