Isabel intensified Thursday into an extremely powerful Category 5 storm as it rolled westward across the Atlantic.
The storm's maximum sustained wind speed began the day at 145 mph, but by 5 p.m. the winds had grown to 160 mph with higher gusts. A hurricane becomes a Category 5, the top of the scale, if its winds reach 156 mph.
The five-day forecast places Isabel roughly 550 miles east of Miami and closing in on the Bahamas, should it maintain its westward course. Forecasters said they would know more about the potential direction of the storm late this weekend.
Hilton Head Island's emergency management coordinator said the town is prepared should Isabel turn toward South Carolina.
Jay Harter said town staff members met Thursday to review evacuation plans, which include making sure the generators are checked and fueled, and the contact numbers are up to date.
"Crossing the T's and dotting the I's to make sure everything's done," he said. "It's something we're prepared for. We're ready."
Harter said even the town is ready to evacuate if needed: Seven-hundred boxes to pack up necessary town records are available.
Steve Fields, deputy director of the Beaufort County emergency management, said Thursday the department was watching the storm, but wasn't doing anything yet to prepare for it.
"At this point, it's business as usual," Fields said.
It's still unclear what impact Isabel could have on South Carolina, said Bernie Palmer, meteorologist in charge of the Columbia office of the National Weather Service.
A cold front from the West is expected to move into the Southeast early next week, he said. But that may come too early to push the hurricane north and creates a "potential period of uncertainty," Palmer said.
By 1 a.m. Saturday, the hurricane is expected to be four days away from the East Coast and possible landfall, said Gov. Mark Sanford's chief of staff Fred Carter.
At that point, state officials will look at strike probabilities to determine whether to begin evacuations and lane reversals in the 96 hours before landfall.
Former Gov. Jim Hodges was criticized in 1999 for not making the call soon enough to help traffic flow from people evacuating the coast when Hurricane Floyd hit. Some motorists spent as long as 18 hours on Interstate 26 between Charleston and Columbia, a trip that normally takes about two hours.
Sanford, who defeated Hodges in the 2002 election, said he learned a lesson from that experience.
"Storms can be damaging in a lot of different ways. They can be damaging to physical property, to people's lives on the coast and they can also be damaging to one's political persona given the way things are perceived to be handled or not handled," Sanford said.
Agency officials said they are ready to handle Isabel. Emergency shelters and law enforcement are ready to operate.
One weakness could be the number of troops available from the National Guard, which already is strained with guardsmen deployed to the Middle East, Adjutant General Stan Spears said.
Spears said South Carolina has an agreement with Georgia and North Carolina to share troops as needed.
Sanford, who has a home on Sullivans Island just north of Charleston, said residents shouldn't be worried this weekend, but they should keep an eye on the storm.
"We're due, unfortunately, at some point," Sanford said.
The last hurricane to develop into a Category 5 in the Atlantic was Mitch in 1998, which moved into the Caribbean Sea and killed 11,000 people and left thousands more missing in Nicaragua, Honduras and Guatemala.
The last Category 5 hurricanes to strike the U.S. coast were Andrew in 1992 and Camille in 1969.
"If anyone remembers those storms, there was extreme catastrophic damage very near the center of where they made landfall," hurricane forecaster Richard Knabb said.
At least three cruise ships have changed their routes to avoid Isabel's path.
Forecasters said the storm could spawn large ocean swells creating hazardous surf conditions in the Leeward Islands, the Virgin Islands and Puerto Rico over the next few days. But Isabel's center will pass well to the north of those islands, so effects should be minor.
The Atlantic hurricane season began June 1 and ends Nov. 30.