Salvo (North Carolina), Sept. 13 (Reuters): Tropical Storm Ophelia threatened to strengthen back into a hurricane as it wobbled toward the southeast US coast today and sent thousands of people packing from North Carolina's barrier islands.

Ophelia’s centre was 232 km south of Wilmington, North Carolina. The storm was creeping north-northwest and was expected to turn north and hit the North Carolina coast tomorrow night and Thursday, the forecasters said.

Ophelia had sat off the North and South Carolina coast for four days, alternately strengthening into a hurricane and weakening back to a tropical storm.

At 1200 GMT, it was a tropical storm with 112 kmph winds but was expected to cross the 119 kmph threshold to become a hurricane again by tomorrow, forecasters at the US National Hurricane Center said.

Along the 160-km chain of barrier islands known as the Outer Banks, mandatory evacuation orders were issued for all 20,000 people on Hatteras Island, a popular vacation spot that includes Cape Hatteras Lighthouse and the Cape Hatteras National Seashore.

“Today is our window of opportunity and we are asking everyone to leave,” said Sandy Sanderson, emergency management coordinator for Dare County, which includes Hatteras Island.

North Carolina officials also ordered everyone off of tiny Okracoke, a low-lying island reachable only by boat or plane, and told visitors to leave coastal Onslow County. Authorities urged people to voluntarily leave other barrier islands, lowlands and coastal towns in North and South Carolina.