A slowly moving and evolving Atlantic storm will affect a 600-mile stretch of the Eastern Seaboard of the United States with areas of rain, gusty winds and rough surf through this weekend.
Enough rain will fall in some areas to cause poor visibility for motorists in parts of the Interstate 85 and 95 corridors. Wind and/or rain in some cities could cause airline delays. Onshore winds along the coast will contribute to coastal flooding and beach erosion.
How significant and widespread these impacts become will depend on the strength of a storm from the Atlantic and its track along the coast.
Rain will first expand inland over the area from Georgia to the Carolinas and southern Virginia through Saturday as one part of the storm system drifts westward.
The rain is likely to reach as far west as the southern Appalachians from Alabama to Virginia and West Virginia. Spotty showers and thunderstorms indirectly associated with the storm will extend as far south as Florida.
Within this swath, there is the potential for a thorough soaking. The greatest potential for torrential rainfall and flash flooding is along the coast from the Carolinas to southeastern Virginia. Rainfall amounts near the coast will generally average 1-3 inches with locally 5 inches into the weekend.
A second part of the storm will attempt to consolidate and cause rain to expand northward along the mid-Atlantic coast this weekend and into early next week.
In the Northeast, this part of the system will have to compete with a wedge of dry air and high pressure over New England.
According to AccuWeather Chief Meteorologist Elliot Abrams, "Sometimes we see this setup cause a storm to strengthen and run northward along the coast and in other times we see the high being too strong, which forces the storm out to sea."
"As a result, the prospect of drenching rain reaching the swath from Washington, D.C., to New York City and Boston later this weekend is not set in stone," Abrams said.
During Saturday and Sunday, clouds will tend to thicken and rain will advance slowly northward over Virginia, the Delmarva Peninsula and southern New Jersey.
The dry air in place will cause some of the rain to fizzle out, but pockets of steady rain may survive, especially along the coast and perhaps over the central Appalachians.
The storm could impact outdoor activities related to the pope's visit in Philadelphia on Sunday.
AccuWeather will continue to provide updates on the storm through this weekend.
Bathers and boaters beware. The most certain aspect of the storm will be stiff winds along the coast with building surf, strong rip currents, coastal flooding and beach erosion.
The flow of air around the high pressure to the north and the storm itself will direct winds and ocean water toward the middle part of the East coast through this weekend.
Winds along the coast can gust past 40 mph.
The effects will occur around the supermoon this weekend.
Tides are likely to average about 2 feet above published levels from South Carolina to New Jersey with moderate coastal flooding possible. Breakers of 6-10 feet are likely at times on top of the raised water levels along this same stretch of coast.
Seas in nearby offshore waters will fluctuate between 8 and 16 feet.
Minor coastal flooding is possible are in store farther north from New York City to Boston and south of Charleston, South Carolina, to Jacksonville, Florida.