The tornado warning for the Washington, D.C., metropolitan area and Mid-Atlantic region has been extended until 2:00am Saturday.
The National Weather Service (NWS) has issued a tornado watch for portions of the District of Columbia, Delaware, central and eastern Maryland, northeast North Carolina, southwestern New Jersey, southeast and east central Pennsylvania, central and eastern Virginia, and coastal waters.
Conditions are considered favorable for tornadoes and severe thunderstorms, including damaging wind gusts of up to 70mph (112kph), hail up to one inch (2.5cm) in diameter and lightning strikes, the NWS warned.
A flash flood alert is also in effect until midnight, covering the District of Columbia, as well as parts of Maryland and Virginia. Rainfall of between 1-3 inches (2.5-7.5cm) has been forecast for the area, with isolated falls of more than five inches (12.7cm) in some areas.
Washington, D.C., area electricity utility Pepco issued a statement saying that it had increased the number of maintenance crew and call center staff working Friday night in anticipation of weather conditions which could cause widespread and extended power outages.
A separate warning was also issued Friday night for severe thunderstorms for portions of central New York state and northeast Pennsylvania and was in effect until midnight. The NWS warned of wind gusts up to 70mph (112kph), hail up to half an inch (1.3cm) in diameter and lightning strikes.
Earlier Friday, officials warned residents in parts of northern Virginia to seek shelter after a thunderstorm capable of producing a tornado was spotted near Dale City, about 25 miles (40km) southwest of Washington, just after 5:00pm local time. The storm was moving northeast at 40mph (64kph).
Some departing flights were delayed at Ronald Reagan Washington National Airport, Dulles International Airport and Baltimore-Washington International Airport due to the storms.