Raleigh: Thousands of people evacuated North Carolina`s barrier islands as a strengthened Hurricane Earl threatened to pound large areas of the US East Coast with heavy winds and rough seas.
The strongest Atlantic storm of 2010 was on a path to lash the North Carolina coast and then move north, wreaking havoc on the end-of-summer, US Labor Day holiday weekend that usually draws millions to the beaches.
At 0300 GMT Thursday, Earl, which earlier regained category four status, had sustained winds of 140 miles (220 kilometres), the National Hurricane Centre (NHC) said.
The eye of the storm was 520 miles (840 km) south-southeast of Cape Hatteras in the Outer Banks -- a narrow band of North Carolina barrier islands.
In a sign the hurricane season was heating up, the NHC said the fourth storm in the past 11 days, Tropical Storm Gaston, had formed in the Atlantic.
Gaston had winds of 40 miles (65 km) per hour and was centred 1,585 miles (2,550 km) east of the Lesser Antilles.
But forecasters warned the storm`s track could well put it in the path of earthquake-hit Haiti, a worst case scenario now threatening to become reality for the still-reeling island nation.
Thousands of quake survivors remain in flimsy, makeshift, open air camps throughout the capital Port-au-Prince and surrounding areas, and observers warn of a further humanitarian catastrophe if the area is hit by a major storm.
US officials, meanwhile, ordered a mandatory evacuation for thousands of visitors plus the estimated 800 residents on North Carolina`s Ocracoke Island, where ferry service is the only means of transportation back to the mainland.
President Barack Obama signed a disaster declaration for North Carolina, declaring an emergency in the state and ordering federal aid to support response efforts.
"The timing is not good for folks trying to enjoy the last good summer weekend, but safety and protection of personal property comes first," said Cyndy Holda, public affairs officer at Cape Hatteras National Seashore.
Just to the north, officials in Dare County issued a mandatory evacuation for visitors to Hatteras Island, the easternmost point in the state.
The storm was expected to pass about 50 miles (80 kilometres) to the east of Hatteras Island early Friday.
Earl was churning northwest at 18 miles (30 kilometres) per hour, prompting watches and warnings along a wide area of the coastline as far north as Massachusetts.
A hurricane warning, meaning hurricane-force winds are expected, was in effect from the Bogue Inlet in North Carolina to the Virginia border.
A hurricane watch, which means dangerous conditions are a possibility, was in effect from the North Carolina-Virginia border to Delaware and all the way to Massachusetts, including the tourist islands of Martha`s Vineyard and Nantucket.
Tropical storm warnings or watches were in effect around the Chesapeake Bay and parts of the New Jersey coast.