Wind and rain started to whirl off the Bahamas on Thursday and could become a tropical storm or worse for the Southeast by the weekend.
Forecasters are expecting the weather to develop into at least a weak tropical storm by Saturday.
How fast that happens and how strong the storm becomes could determine whether it makes landfall in Florida or works its way along the Southeast coast.
"There are three scenarios here," said Charleston-based meteorologist Shea Gibson, with the forecasting company WeatherFlow. "Westward across Florida, northwards up the Florida coast towards the Carolinas or north then northeast to hook away from the coast. It's too soon to dial in on any particular one, but keep monitoring it."
At a minimum, the storm will make for a rainy late weekend for South Carolina. At worst, it could strengthen to Hurricane Humberto just offshore, on a path resembling Hurricane Dorian last week.
Either way, the storm is expected to drench the Bahama islands still flooded and in ruins from Dorian.
"A quicker-forming and more intense system would be more likely to stay offshore of Florida and recurve to the north and then northeast," said meteorologist Jeff Masters of the forecasting company Weather Underground.
"A weaker and slow-to-consolidate system would be more likely to be steered by the low-level trade winds and move northwest across Florida and into the Gulf of Mexico," he said.
Computer model runs on Thursday wavered over just where this storm will head.
The National Hurricane Center continued to call for the storm to make landfall in Florida after raking the Bahamas and began issuing advisories. Center specialist Lixion Avila called for it to intensify near the east coast of Florida. The forecast expected it to strengthen to 50 mph winds before landfall by Sunday.
However, "Given the (computer) model discrepancy, both the track and intensity forecasts are highly uncertain, more than usual," Avila said.
The National Weather Service office in North Charleston cautioned residents that the trend in computer model runs suggested the storm could move into southeast Georgia or South Carolina.
"However uncertainty is very large regarding the potential track of the system at this time," service forecasters said.