The hurricane weakened slightly but was still packing winds of 170 kilometers (105 miles) an hour as it came out of the Atlantic.

With experts predicting the storm would hit land on Thursday, thousands of home and store owners along the coast boarded up their windows and rushed to buy extra supplies of emergency food, batteries and first aid kits.

Immediate predictions were for the storm to make land around North Carolina and then sweep up the East Coast.

Authorities ordered people in Dare county in North Carolina to leave their homes from midday (1600 GMT).

The community on the low lying island chain has about 23,000 permanent residents but the population swells to 150,000 in the summer peak season. Many homes are precariously perched on stilts.

Sergeant Frank Pierce, a state public safety spokesman, said "There are not a great deal of tourists right now."

Residents and vacationers in nearby Ocracoke Island were also ordered to evacuate, reports said.

North Carolina Governor Mike Easley urged people "to stock up on needed supplies such as gasoline and water, and tune to news broadcasts to hear the latest updates from emergency management personnel."

Virginia state, just to the north, declared a state of emergency late Monday so that it could prepare for the storm.

US warships began steaming out of the giant US naval base at Norfolk, Virginia to get out of Isabela's path.

Up to 40 submarines and warships, including the carrier USS Ronald Reagan, will get underway Tuesday to ride out the hurricane at sea, the US navy said in a statement.

A spokesman for the Atlantic Fleet said the ships were to leave port every 10 to 15 minutes, and F/A-18 and F-14 fighters based at nearby Oceana Naval Station also have been ordered to disperse to other bases beyond the reach of the storm.

At 1500 GMT, a hurricane watch was in effect from Little River inlet in South Carolina to Chincoteague, Virginia, meaning it could hit in about 36 hours, according to the US National Hurrican Center.

The center of Isabel was located 965 kilometers (600 miles) south-southeast of Cape Hatteras, North Carolina, moving north-northwest at about 8.0 miles (12.8km) per hour.

As the maximum sustained winds had decreased Isabel was reduced to a Category Two hurricane on the Saffir-Simpson hurricane scale, which goes up to five.

The center said that while some further weakening was expected, it could strengthen again before hitting land.

Hurricane force winds extend outward up to 120 miles (195 km) from the storm's center and tropical storm force winds extend outward up to 230 miles (370 km), it warned.

"Large ocean swells and dangerous surf conditions are already being experienced along portions of the US Southeast and mid-Atlantic coasts. These conditions will also continue over portions of the Bahamas for the next few days," said the warning.

Even where it does not hit the mid-Atlantic US shoreline, Isabel will still bring high winds, rain, dangerous surf and riptides to the US coast.

"That is a virtual guarantee," said Eric Blake of the Miami-based center. "Even if it missed you by 100 miles, you will still feel its effects."

TERRA.WIRE