(HATTERAS ISLAND, N.C. (Reuters) - The first hurricane of the Atlantic season gained strength on Thursday and was expected to attain Category 2 status as it reached the North Carolina coast in the United States, where thousands of vacationers scrubbed their July Fourth Independence Day holiday plans amid evacuation orders.
Hurricane Arthur was about 150 km south-southwest of Cape Fear, North Carolina, with maximum sustained winds of 145 km per hour, U.S. forecasters said.
Moving faster at 20 kph, the centre of the storm was expected to brush the North Carolina Outer Banks late Thursday and early Friday with winds reaching up to 170 kph, according to the U.S. National Hurricane Centre in Miami.
Arthur would be the first hurricane to hit the United States since Superstorm Sandy devastated New York and New Jersey in October 2012 and caused US$70 billion estimated damage.
Despite growing in intensity, Arthur remained a relatively small storm, with hurricane force winds only extending outward up to 35 km from the centre. After grazing the Outer Banks, Arthur should accelerate toward the northeast and remain offshore on Friday as it diminishes in strength, posing no risk to the northeastern United States, forecasters said.
"The worst of Arthur's wind will remain offshore, but some strong, gusty squalls will affect the North Carolina barrier islands," said Dan Kottlowski, a hurricane expert at AccuWeather.
The hurricane centre did note on Thursday afternoon, however, that "only a slight westward shift in the track would bring the strongest winds inland over eastern North Carolina".
The storm disrupted plans for holiday beachgoers and others ordered off low-lying barrier islands in the storm's path. Tourists and some residents packed ferries and crowded the only highway off Ocracoke and Hatteras islands, where voluntary and mandatory evacuations were in effect.
Ferry service between some islands was suspended on Thursday afternoon as conditions began to deteriorate, with heavy rain and wind gusts reported along the coast. Some people on Hatteras Island planned to ride out the storm.
Retiree Gerry Lebing said he was tying things down at his house and moving cars to higher ground. Troy Scroggin drove from Virginia to check on his vacation home on Hatteras Island.
"We had to batten down the hatches and we're going to stay and see what's it's like," he said. The storm could bring life-threatening rip currents and a storm surge of up to 1.2 metres to North Carolina's barrier islands, forecasters said.
North Carolina officials warned the storm surge could make the narrow 80 km Highway 12 connecting Hatteras Island to the mainland impassable. The state was putting extra heavy equipment in place to remove sand and the overwash as soon as possible after the storm passes.
Part of the highway was washed out by storm surge for two months after Sandy, forcing people to use ferries to reach the mainland.
"I think it's probably going to get knocked out again," said Jeff Masters, a hurricane expert with private forecaster Weather Underground. Officials asked residents to stay out of rough waters and avoid driving through high water.
"Don't put your stupid hat on," North Carolina Governor Pat McCrory said at a news conference.
State officials said 105 National Guard members have been deployed to help with storm preparation and safety, and 400 state troopers are helping with the evacuation efforts.
"There could be loss of electricity, there could be restaurants closing, there could be cars flooding and roads could be compromised," Hyde County Manager Bill Rich said. Several towns and villages on North Carolina's coast rescheduled Independence Day festivities and fireworks as the storm approached.
Farther north, the beach resort of Ocean City, Maryland, moved its July Fourth fireworks display to Saturday. Boston officials moved up to Thursday a nationally televised concert by the Boston Symphony Orchestra and a fireworks display, which draw hundreds of thousands of spectators to the city's riverfront. Despite losing strength on Friday, Arthur would likely bring heavy rain to Boston and strong winds over Cape Cod and Nantucket. It would still be near hurricane strength when it passes over Nova Scotia on Saturday, according to Masters.