The Washington area remained under a severe thunderstorm watch until 8 p.m. after a fast moving storm with heavy rain, hail and wind gusts swept through during the evening rush hour, the National Weather Service reported.
Shortly after 6 p.m., Doppler radar showed thunderstorms near Camp Springs in Prince George's County and also over eastern portions of the District., moving east at 20 mph, the service reported.
Earlier thunderstorm warnings, a higher level alert than a watch, in the District, Alexandria, Arlington, Fairfax, Prince George's and Anne Arundel counties were allowed to expire. Severe thunderstorm warnings for Talbot County on Maryland's Eastern Shore were in effect until 7:30 p.m.
At 4:20 p.m., the weather service reported a severe thunderstorm over Northern Virginia, moving east from Baileys Crossroads at 15 mph. Hail up to an inch and a half in diameter was reported falling near Falls Church.
Shortly after the storm hit Virginia, Dominion Virginia Power estimated 23,800 customers in the Herndon and Sterling areas were without power. The utility serves about 700,000 people in Virginia.
"It's widespread," spokeswoman Le-Ha Anderson said of the thunderstorm. "It brought some high winds and hail about the size of golf balls."
National Weather Service meteorologist Luis Rosa tracked conditions from his Sterling office and said the hail ranged from "penny-sized to golf ball-sized." He credited cold air in the upper levels of the atmosphere for causing the storm.
Reagan National Airport and Dulles International Airport reported weather-related delays -- some of them more than three hours -- for flights departing for airports in the Northeast. A number of arriving flights were delayed or canceled. Passengers were urged to check with their airlines to determine whether their flights were affected.
Rosa said Tropical Storm Bonnie will likely bring heavy rainfall to the region Thursday into Friday morning.
He said he is still trying to track Tropical Storm Charley, but predicted a Saturday arrival.