CHARLESTON, S.C. — A hurricane watch was posted yesterday for the Southeast coast as Ophelia strengthened into a hurricane once again and meteorologists said its meandering course could take a sharp turn toward land.

A hurricane watch was posted along a 300-mile stretch from the Georgia-South Carolina line to North Carolina's Cape Lookout, meaning hurricane-force wind of at least 74 mph was possible by this evening, the National Hurricane Center said.

South Carolina state emergency officials said a decision would be made soon about whether to order evacuations, but Charleston County announced yesterday it would open shelters for voluntary evacuees from low-lying areas and barrier islands.

"We don't think it's a done deal yet," said Joe Farmer, a spokesman for the South Carolina Emergency Management Division. "It's moving really slow, so we have to hang with it. But there is some expectation it will move toward the coast."

Emergency-management directors along the North Carolina coast said they were prepared for Ophelia and warned residents not to be complacent.

The crew of an Air Force hurricane-hunter airplane flying through Ophelia measured top sustained wind of 80 mph.

It could strengthen a bit before an expected landfall tomorrow, said Eric Blake, a meteorologist at the hurricane center in Miami.

"Almost every [computer] model indicates a United States landfall," he said. "It's time to make those preparations."

At 11 p.m. EDT yesterday, Ophelia was centered about 255 miles east-southeast of Charleston, S.C., and about 235 miles south of Cape Hatteras, N.C. It was expected to head to the northwest, toward the coast, today.

The forecasters said the storm most likely would strike between Myrtle Beach, S.C., and Moorehead City, N.C.

Ophelia is the seventh hurricane in this year's busy Atlantic hurricane season, which began June 1 and ends Nov. 30. Peak storm activity typically occurs from the end of August through mid-September.