Torrential rain and locally gusty thunderstorms are converging on the mid-Atlantic on Friday, raising the risk of flash, urban and stream flooding. Heavy rain will push across New England Friday night into Saturday.
The heaviest and most persistent rainfall and greatest risk of flooding Friday morning reaches from eastern North Carolina and the Chesapeake Bay region northward through eastern Pennsylvania, central upstate New York. The rain will continue to advance slowly to the east over the mid-Atlantic and New England.
A general 1 to 2 inches of rain will fall along the I-95 corridor with higher amounts of up to 2 to 4 inches falling over much of the southern and central Appalachians to the lower Great Lakes. However, locally higher amounts are possible throughout the eastern third of the nation.
Enough rain has fallen in Virginia and Maryland to cause small stream flooding and will push some of the major rivers to moderate flood levels into the weekend. This includes portions of the Potomac River. Similar problems have been occurring with streams and can continue to evolve along some of the rivers in portions of upstate New York and Pennsylvania.
Multiple secondary roads have been closed from North Carolina to Virginia, where between 2 and 6 inches of rain fell Thursday into early Friday morning. Some roads have been washed out and multiple basements have been flooded. Flash flooding forced evacuations in Chapel Hill, North Carolina and in some of the suburbs around Washington, D.C.
Portions of upstate New York around the Finger Lakes have been hit with heavy rain, flooding and road closures for the second time this week.
Major cities that will be impacted by a six- to eight-hour episode of drenching showers and thunderstorms include Baltimore, Philadelphia, New York City, Albany, New York, Hartford, Connecticut, and Boston. While the intense rainfall and poor visibility may only last a few hours, the impact on travel and outdoor activities may linger longer.
According to Northeast Weather Expert Dave Dombek, “The timing of the rain is such that Washington, D.C., and Baltimore have the greatest impact Friday morning, while around New York City the worst of the rain will be Friday evening with problems during much of the day around Philadelphia.”
The heaviest rain is scheduled to swing through Boston Saturday morning and midday.
For fans heading to MLB games Friday, especially in the Northeast, be sure to check with schedule in case of a postponement. Games most likely to be affected by downpours during or just prior to scheduled play are the Reds at Phillies and Pirates at Yankees.
Gusty thunderstorms will accompany the heavy rainfall in some areas and can erupt ahead of the steady rain area.
According to AccuWeather Senior Meteorologist Brett Anderson, “The combination of thunderstorms and strong winds aloft could bring gusts to 60 mph on Friday in the mid-Atlantic, especially from eastern Pennsylvania and New Jersey through Delmarva.”
Moisture from the Gulf of Mexico, the Atlantic Ocean and the tropics will be drawn into the system as it crawls eastward through Thursday, then begins to lift northeastward Friday into Saturday at a faster past.
“Most areas in the I-95 zone have had a long gap since the last heavy rainfall [late April], so that only minor flooding problems are likely, but it is a different story farther inland and the flooding risk is greater as a result,” Dombek said.
Where the heaviest rainfall occurs, over the Appalachians and lower Great Lakes, lives and property can be threatened in some communities that are prone to flash flooding.
As the system passed through the Central states earlier this week, it had a history of causing flash flooding. In addition, the zone of tropical moisture forecast to feed in along the Atlantic coast produced flash flooding and mudslides in Puerto Rico and the Virgin Islands this past weekend.
In the wake of the drenching rain, cooler air will roll eastward from the Midwest in time for the weekend. Similar to a storm that brought cool and unsettled conditions to the area a week ago, this new storm has the potential to bring building clouds and spotty showers mainly during the afternoon and evening hours.
Beneath the storm, high temperatures may be held in the 50s over the mountains and the lower 70s in many areas east of the Appalachians.
More at AccuWeather: Virginia to New York: Rain Triggers Delays, Flooding