MIAMI — Tropical Storm Florence is expected to strengthen into a "major hurricane" Saturday evening, the National Hurricane Center said. It is expected to approach the southeastern U.S. Coast on Thursday.

Florence was centered about 810 miles southeast of Bermuda and moving west at 5 mph, the hurricane center said in 5 p.m. EDT advisory. Its sustained winds were estimated to be 70 mph.

North Carolina Gov. Roy Cooper declared a state of emergency on Friday evening, urging residents to use the weekend to prepare for the possibility of a natural disaster. "We are entering the peak of hurricane season and we know well the unpredictability and power of these storms," he said.

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In South Carolina, Gov. Henry McMaster declared a state of emergency Saturday to prepare for the storm, stressing the declaration is not an order to evacuate.

"It's a beautiful day outside, people playing football, the last thing on people's mind is a hurricane," McMaster said, according to The State newspaper. "Just like they got ready to play these football games today, we're asking people to get ready."

This map from the National Hurricane Center shows the projected path of Tropical Storm Florence on Saturday, September 8, 2018. National Hurricane Center

The U.S. Navy is making preparations this weekend for its ships in the Hampton Roads area to leave port to avoid storm damage as the storm approaches. Adm. Christopher Grady said the decision was based on Florence's current track, which indicates the area could see strong sustained winds and storm surges.

Swells generated by Florence could cause dangerous rip currents and coastal flooding Saturday in areas including coastal Delaware and New Jersey, the National Weather Service said.