A tropical storm warning and a hurricane watch have been issued for the entire North Carolina coast as tropical storm Arthur, plus a cold front moving over the East Coast, is expected to bring heavy rains that could dampen some July 4 celebrations, or push them off to later in the weekend.
At 11 a.m. EDT Wednesday, Arthur was centered east northeast of Cape Canaveral, Fla., heading north at about seven miles an hour. Arthur packs maximum sustained winds of 60 miles an hour. Those speeds must exceed 74 miles an hour to be classified as a hurricane.
Tropical-storm-force winds extend up to 80 miles from Arthur's center.
Arthur's current track has it skirting Cape Hatteras, N.C., on Thursday night as a Category 1 hurricane. From there, it makes a beeline for Nova Scotia. Along the way, Arthur is projected to pass about 200 miles east of Cape Cod, Mass., on Saturday morning.
In Boston, where the Boston Pops orchestra is slated to hold its revered, annual July 4 concert, capped off with a fireworks extravaganza over the Charles River, city officials are weighing a change to the event's date because of the heavy rains and thunderstorms forecast for July 3 and 4.
Early on Wednesday, some had still held out hope that the concert and fireworks display could proceed as scheduled. David Epstein, a meteorologist at Framingham State University in Framingham, Mass., and correspondent for Boston.com, had suggested a 65 percent chance for a break in the weather that would last long enough to accommodate the concert and fireworks. But later, as new data became available, the forecast took a grim turn, with heavy rains swamping eastern Massachusetts and Rhode Island at concert time.
In New York, forecasters suggest that the wet weather will move out in time for a fireworks show sponsored by Macy's – a show slated to begin at 9 p.m. Farther south, in Philadelphia, any showers are expected to end around noon on the Fourth.
For Cape Hatteras, Arthur is expected to arrive Thursday, with hurricane conditions possible overnight Thursday and tropical storm conditions lingering on the Fourth as the storm moves northeast.
While Arthur is the major influence for a soggy holiday for North Carolina, in the Northeast, the dominant factor in potential holiday rainouts is a cold front moving into the region, with heavy rain expected from Wednesday night through Friday night.
An influx of warm moist air driven onshore by Arthur's broad circulation ahead of the storm will contribute some moisture to the region northwest of the storm's path, notes Andrew Orrison, a meteorologist with the National Weather Service's Weather Prediction Center in College Park, Md. But unless Arthur's track slides west of its currently projected path, the cold front's passage over the Northeast will be the key player, he says.
The major risks from Arthur stem from storm surge, as well as rip currents along beaches up and down the East Coast, forecasters say. A new surge-forecast tool that the National Hurricane Center has released on an experimental basis shows the potential for surges of up to three feet above ground level for a wide swath of the coast – from Islamorada in the Florida Keys to False Cape State Park, south of Virginia Beach.
Some locations, especially along the North Carolina coast, could see surges of up to six feet.
The forecast period runs from 5 a.m. Wednesday through 10 a.m. Saturday.
Rip currents, however, present the longest-lasting risk to holiday beachgoers, forecasters warn.