The Storm Prediction Center, in Norman, Okla., has placed the entire region under the "slight-risk" zone for severe weather with high winds and possible hail Thursday.
Arthur was forecast to grow into a Category 1 hurricane by day's end Thursday, with peak winds at 75 m.p.h., just 1 m.p.h. over the hurricane threshold. Eventually, those winds are expected to reach 85 m.p.h.
While Arthur won't directly affect the immediate Philadelphia region, it could deliver plenty of sound and fury. An approaching front that has been plowing its way through the oppressive atmospheric soup over the region is expected to lure some of Arthur's moisture toward the northwest.
The first named storm of the Atlantic hurricane season prompted a tropical-storm warning for the entire North Carolina coast and had officials, hotel owners, and would-be vacationers as far north as New England carefully watching forecasts.
Officials in Dare County, N.C., where at least 250,000 vacationers are spending their Fourth of July holiday, were to decide late Wednesday whether to call for evacuations.
A countywide state of emergency was declared in neighboring Hyde County, where officials called for a voluntary evacuation of Ocracoke Island. Gov. Pat McCrory declared states of emergency in 26 counties.
In Boston, officials decided to move the annual Boston Pops July Fourth concert and fireworks show up by a day because of potential heavy rain Friday night.
Forecasters say the size and path of the storm are still uncertain, but beach patrol officials - including Kent Buckson, head of the Rehoboth Beach Patrol, and officials in Ocean City, Md. - say a tropical storm or hurricane doesn't have to be close to shore to cause heavy surf and dangerous rip currents. Those rip currents could be especially troublesome if sunny skies Saturday draw lots of people to the water.
Locally, Arthur should be over by late in the day Friday. By nightfall, the skies should clear - with a 100 percent chance of fireworks.
This article includes information from the Associated Press and Bloomberg.