(Updates location and speed in second paragraph.)
July 2 (Bloomberg) -- Tropical Storm Arthur grew to almost Category 1 hurricane strength off the coast of Florida, prompting alerts as far north as Virginia.
The system was about 180 miles (290 kilometers) south- southeast of Charleston, South Carolina, with maximum sustained winds of 70 mph, moving north at 8 mph, the National Hurricane Center in Miami said in an advisory at 8 p.m. local time. A storm becomes a hurricane when its winds reach 74 mph.
“Arthur is a strong tropical storm right now,” said Paul Walker, a meteorologist at AccuWeather Inc. in State College, Pennsylvania. “The storm will continue to strengthen and should reach hurricane strength maybe by tonight.”
The Atlantic season’s first storm would also be the first hurricane to hit the U.S. since 2012 if it reaches that level and strikes North Carolina’s Outer Banks. Its movement up the coast will also stall a cold front out of the western U.S., triggering heavy rains along the Eastern Seaboard.
Officials in Dare County, North Carolina, where at least 250,000 vacationers are spending their Fourth of July holiday, issued a mandatory evacuation order for Hatteras County beginning tomorrow.
A countywide state of emergency was declared in neighboring Hyde County, where officials called for a voluntary evacuation of Ocracoke Island. North Carolina Governor Pat McCrory declared states of emergency throughout coastal portions of the state.
With winds of at least 74 mph and pounding surf expected in the next 36 hours, a hurricane warning was issued from Surf City to Duck, as well as Pamlico Sound and eastern Albemarle Sound in North Carolina, according to the hurricane center.
A hurricane watch is in effect from Little River Inlet to south of Surf City.
Storm surge of as much as 4 feet (1.2 meters) is possible along the coast of North Carolina and 1 to 3 feet in South Carolina, the center said.
Tropical storm watches and warnings stretch from the Santee River in South Carolina to the Cape Charles Light in Virginia.
Cape Cod in Massachusetts is expected to be struck by tropical storm conditions this weekend as the storm passes, the National Weather Service in Taunton, Massachusetts, said.
“Interests along the U.S. East Coast north of the warning area, primarily in southeastern New England, should monitor the progress of Tropical Storm Arthur,” the hurricane center said.