Hurricane Isabel became a powerful Category 4 storm late Monday night but is still too far away to determine what effect it could have on the Grand Strand.

The storm is expected to pass north of Puerto Rico on Sunday, said Dave Loewenthal, a forecaster with the National Weather Service in Wilmington, N.C.

Tropical Depression 14, forming behind Isabel in the Atlantic, is weakening while moving north near 12 mph over the Cape Verde Islands.

Georgetown County emergency officials are hoping a high-pressure system will allow Isabel to curve north.

Isabel, however, is predicted to hold a western track longer than Hurricane Fabian, which struck Bermuda last week.

"We're keeping an eye on it at this point," said Georgetown County Emergency Services Director Mike Mock. "We'll see where it is Friday to see what decisions need to be made. It is a Category 4 storm, so it bears watching."

The Northern Leeward Islands could receive their first hurricane warnings in the next four days, Loewenthal said. A hurricane watch is issued when a storm is expected to strike within 36 hours.

Hurricane Hugo, which struck Sept. 21, 1989, in Charleston, became a Category 5 storm before it approached the Caribbean Sea.

Hugo caused damage in Puerto Rico, then strengthened before hitting South Carolina.

Forecasters can't predict Isabel's path after this weekend.

"The forecast only goes to the 12th," Loewenthal said. "We'll have to take it day by day. It won't get real critical after the weekend. If it were going to affect the East Coast, it would be 10 days or two weeks away."

At 11 p.m. Tuesday, Hurricane Isabel had maximum sustained winds near 135 mph and was about 875 miles east-northeast of the northern Leeward Islands.

Isabel is moving west-northwest near 14 mph and is expected to make a turn to the west during the next 24 hours.

The National Hurricane Center stopped issuing advisories Monday on weakening Hurricane Fabian, which was moving into the north Atlantic.

The Associated Press contributed to this report.Contact KELLY MARSHALL at 520-0497 or kmarshall@thesunnews.com.