Hurricane Irene battered Puerto Rico overnight with damaging winds and flooding rains, then veered north of Hispaniola's mountains on a course that will allow it to become a strong hurricane as it approaches the U.S. Southeast coast -- possibly the Carolinas -- later this week.

The National Hurricane Center's official forecast is for Irene to be a 115-mph hurricane when it makes landfall early Saturday near Myrtle Beach, but meteorologists cautioned that much of the coast -- from south Florida up to the Outer Banks -- could be the landfall site.

Meanwhile, some meteorologists said trends indicate Irene could do what many other hurricanes have done -- curve away from the U.S. coast.

The Hurricane Center's official forecast nudged the landfall site northward Monday morning. The 5 a.m. prediction was for landfall near Savannah, but with the computers indicating a weakness in the atmosphere could allow the storm to move farther north before encountering the mainland, meteorologists pushed the expected landfall location north to the Grand Strand. National Hurricane Center meteorologists said they expect to have more data on which to base a forecast later Monday.

The latest forecast would lessen the direct impact of the storm on the Charlotte region, keeping strong winds and heavy rain in the eastern half of the Carolinas.

Meteorologists earlier expected Irene to cross the 10,000-foot mountains of the Dominican Republic, which would have disrupted the storm's circulation. But because the hurricane is slipping north of Hispaniola, that means Irene will be able to intensify considerably as it crosses warm water on route to the Bahamas and the Southeast U.S. coast.

Stacy Stewart of the National Hurricane Center cautioned people not to make too much of the Friday and Saturday portions of the predicted path for Irene. "It is important not to forecast on the exact forecast track, especially at days 4 and 5," Stewart said Monday morning. "Since the most recent five-year errors at those forecast times are 200 and 250 miles, respectively."

At 11 a.m., the center of Hurricane Irene was at 19.2 degrees north and 67.5 degrees west, or 105 miles west-northwest of San Juan, Puerto Rico. It was moving west-northwest at 13 mph, with top sustained winds of 80 mph.

Hurricane warnings were in effect for the southeast Bahamas, the Turks and Caicos islands, Puerto Rico, and the north coast of the Dominican Republic. A hurricane watch was posted for the north coast of Haiti and the central Bahamas. And tropical storm warnings were in effect for the the south coast of the Dominican Republic and Haiti.

Irene was a tropical storm when it moved across the U.S. Virgin Islands on Sunday evening, but it reached hurricane strength before daybreak Monday. It was the first hurricane of the season in the Atlantic-Caribbean basin.

Stewart said there was widespread tree and power line damage reported from across Puerto Rico, and that more than 1 million customers were without power. But no deaths were reported.

Flooding was reported across the island, and Gov. Luis Fortuno warned residents to stay indoors, to avoid downed power lines and flooded areas.

"This isn't the time to go out to find out what happened," Fortuno said. "This is the time to stay in your homes."

Along the Southeast coast, emergency management officials began taking notice.

Officials in Charleston warned residents and vacationers to monitor the storm. Joe Farmer, of the S.C. Emergency Management Division, told the Associated Press it has been six years since a hurricane hit the South Carolina coast.

Authorities in Palm Beach County, Fla., told staffers to stop their routine operations and switch to storm operations.

But Florida officials got some good news late Monday morning from Lexion Avila, of the National Hurricane Center.

"Although it is too early to be certain," Avila said, "the current guidance lessens the threat to south Florida."

In Puerto Rico, the Associated Press reported crews were out cleaning streets and assessing the damage. But officials gave no indication when power would be restored. Schools, most government offices, and many businesses remained closed.

The storm made landfall not far from the town of Humacao. in the southeast part of the island. Emergency director Orlando Diaz told the Associated Press that damage seemed to be less than he had feared.

"We thought things were going to be a bit more trafic," Diaz said. "I was surprised that we didn't see the amount of rain I expected."

In the Dominican Republic, officials assured residents they had food available for 1.5 million people if needed. Also, soldiers and emergency management crews evacuated dozens of residents from high-risk areas along the southern coast.

"We have taken all precautions," presidential spokesman Rafael Nunez said.

Many stores in the capital of Santo Domingo closed Sunday even as people bought last-minute items like flashlights.

The Associated Press' Danica Coto contributed.