At its present course and speed, the center of Florence will likely approach the SC or Georgia coastline on Thursday or Friday. South Carolina Gov. Henry McMaster emphasized that there's no way to know yet when and where the storm will hit land, or when evacuations might be called.
A number of storms are in the Atlantic Ocean, some with the possibility of becoming Hurricanes.
The governors of North and SC both issued states of emergency ahead of the storm.
With the region now in Florence's tentative projected path, weather officials are advising area residents to start making preparations.
Meanwhile, two low pressure systems off the coast of Africa behind Florence also had high chances of developing into tropical storms, forecasters said. "Florence continues on a track to impact the United States mainland by Thursday or Friday".
Trump turns up the heat in trade conflict with China
The tweet came after Apple warned that Trump's proposed tariffs on $200 billion of Chinese-made products would affect the company. Japan will have a "big problem" if it doesn't conclude a new trade deal with the United States , he said on Air Force One.
"However, given the uncertainty in track and intensity forecasts at those time ranges", the National Hurricane Center tweeted, "it's too soon to determine the exact timing, location, and magnitude of those impacts".
Improving atmospheric conditions were expected to allow Florence to regain its former strength. The storm was centered about 905 miles (1,457 kilometers) east-southeast of Bermuda and moving west at 8 mph (13 kph).
Florence continues to strengthen on Sunday and will likely become a major hurricane by Monday.
At least 67 named storms have passed within 200 nautical miles of where Florence has been travelling since 1851.
The storm's sustained winds reached 75 mph (121 kph), just over the threshold for a hurricane, on Sunday morning as it was moving across the Atlantic, about 750 miles (1,210 kilometres) southeast of Bermuda. Emergency officials have told residents to expect immediate threats of ocean swells, unsafe rip currents and coastal flooding. Florence's immediate threat for residents includes large ocean swells, risky rip currents and coastal flooding.
Heavy rain could also cause catastrophic flooding well inland from where the storm makes landfall, which is possible anywhere from Florida to New England, AccuWeather said.