Hurricane Earl began to strafe North Carolina's barrier islands with dangerous winds and surf on Thursday as it spun parallel to the U.S. East Coast on a northward trek towards New England and Canada.

Earl was a massive Category 3 storm on the five-step Saffir-Simpson scale of intensity and had top sustained winds of 115 mph (185 kph) after weakening from its expected peak on Thursday, the U.S. National Hurricane Centre said.

As oil refineries, exploration and drilling platforms, and nuclear power plants along the Atlantic seaboard monitored Earl's path, EnCana Corp said it suspended drilling and pulled personnel from a Nova Scotia rig in Canada.

Exxon Mobil said it had pulled nonessential staff from its Sable field in offshore Nova Scotia.

At least 100,000 people were ordered to evacuate from North Carolina's Outer Banks islands as Earl bore down on the Atlantic shore. It was about 185 miles (300 km) south of Cape Hatteras at 5 p.m. EDT (10 p.m. British time).

It was due to pass near the Outer Banks overnight, making its closest approach near Cape Hatteras around 2 a.m. EDT (0600 GMT) on Friday, before turning gradually northeast to sweep up the East Coast on Friday and into Canada on Saturday.

Even if the Centre of Earl remains offshore, hurricane-force winds are expected to occur in the Outer Banks by tonight, the hurricane Centre forecasters said. Tropical-storm-force winds will likely reach the coast from Virginia northward to Massachusetts on Friday.

The U.S. Census Bureau estimated 26 million people in coastal counties from North Carolina to Maine could feel Earl's effects in the next two days.

While a direct U.S. landfall was not forecast, Earl was due to deliver a stinging blow to the North Carolina coastline and farther northward before the Labour Day holiday weekend marking the end of the summer vacation season.

Forecasters warned that hurricane-force winds from Earl extended out 70 miles (110 km) from its Centre, so it would not need a direct landfall to inflict damage from strong wind and high seas.

The U.S. Energy Information Administration said about 1.1 million barrels per day (bpd) of oil refining capacity lies in the likely U.S. affected area.

Breaking waves 15 feet (4.6 metres) or higher were expected along North Carolina's Outer Banks, picturesque barrier islands that jut out into the Atlantic and are frequently smacked by hurricanes and storms. Earl was one of the biggest storms to menace the state since Hurricane Floyd killed more than 50 people in North Carolina in 1999.

THIS ONE MAY BE BAD

On Ocracoke Island, charter boat captain Ryan O'Neal, 31, said he was staying put with his dog despite an evacuation order. He spoke as the last ferry off the island, accessible only by boat, left on Thursday morning.

I've been here for every hurricane since I was born. This one may be bad, but I'm sure we've had worse. I've got to watch out for my house and boat, O'Neal said.

Watches and warnings were posted along the Atlantic coast for North Carolina, Virginia, Maryland, Delaware, New Jersey, New York, Connecticut, Rhode Island, Massachusetts, Maine and parts of Canada's Nova Scotia and New Brunswick provinces, alerting residents hurricane and tropical storm conditions were possible in the next day or so.

David Rauch, check-in office manager at a 146-unit time-shared resort near Kitty Hawk in North Carolina, said the establishment was nearly full on Thursday morning when employees started notifying residents of an evacuation order.

We've never had a bad hurricane in all the years I've been here. But the fact is that this one is the closest I've seen to having that opportunity to very easily wobble over to the west and hit us real good, said Rauch.

Forecasters said Earl's Centre was expected to be very near southeastern New England on Friday night.

Nantucket, the (Martha's) Vineyard and the eastern half of the Cape (Cod) will experience hurricane-force winds, National Hurricane Centre Director Bill Read said.

Few vacationers were visible along Main Street in Hyannis, normally one of the busiest towns in the beach community of Cape Cod, which is expected to feel the storm on Friday.

We were tempted to leave, but I think we'll stick it out, said John Tracy, 58, of Newport, New York, who was in town to visit his daughter.

DON'T WAIT

Federal Emergency Management Agency Administrator Craig Fugate urged coastal residents to stay alert and heed evacuation orders.

People need to be rapidly completing their preparedness now, Fugate said. Don't wait for the forecast every six hours and think it's going to get better.

Massachusetts Governor Deval Patrick declared a state of emergency, an administrative step that speeds storm relief.

Cars lined up to get off the island resort of Nantucket off Cape Cod and hundreds of boats were removed from its main harbour. Smaller ferry line back-ups were seem on Martha's Vineyard, the island that recently hosted the Obama family's summer vacation and is home to many celebrities.

No storm has threatened such a broad swath of the U.S. shoreline -- the densely populated coast from North Carolina to New England -- since Hurricane Bob in 1991.

Behind Earl, Tropical Storm Gaston dissipated in the central Atlantic. There was still a chance it could regenerate as it moved west towards the Caribbean Sea, but it was too early to tell whether it would enter the energy-rich Gulf of Mexico.

(Additional reporting by Tom Brown and Jane Sutton in Miami, Joe Silha in New York, Ros Krasny in Boston and Scott Malone in Hyannis; Writing by Jane Sutton; Editing by Pascal Fletcher and Jerry Norton)

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