A band of severe thunderstorms swept across a broad swath of Maryland yesterday, from Carroll County to the Lower Shore, disrupting power to thousands of homes, closing the Capital Beltway and prompting tornado warnings by the National Weather Service as meteorologists tracked alarming Doppler radar readings.
The cluster of storms, which formed in central Pennsylvania, turned skies ominously dark as they moved into the region, generating pockets of heavy showers and fierce winds. The storms downed power lines, toppled trees onto homes and produced lightning that set fire to a Montgomery County barn.
Wind gusts clocked as high as 78 mph forced the closure of the Capital Beltway between the Greenbelt Metro station and Baltimore-Washington Parkway for about an hour of the evening rush after power lines fell across the roadway and electrified guardrails, according to state police.
Traffic was allowed to resume about 5:45 p.m. after Prince George's County firefighters and Pepco crews removed the lines.
The weather service office in Sterling, Va., issued a tornado warning at 6:31 p.m., when Doppler radar indicated a severe thunderstorm with strong rotation two miles west of Ironsides in Charles County, as the volatile storm system moved southeast toward the Virginia-Maryland border at 15 mph.
Four minutes later, hail the size of pennies and quarters reportedly pelted the area southwest of La Plata, where a deadly tornado that generated winds exceeding 207 mph struck in April last year.
The weather service received no reports of tornadoes or funnel clouds before the warning expired at 7 p.m.
In Central Maryland, the storms knocked out power for about 93,000 customers of Baltimore Gas and Electric Co. by 8 p.m., said spokesman Clay C. Perry.
Anne Arundel County was hardest hit with some 50,000 losing power, largely because of falling tree limbs and lightning striking transformers, while Howard County had 17,000 and Carroll County had 7,000, Perry said. The utility has about 1.14 million customers.
Perry said BGE crews anticipated the storms and had been on standby to dispatch to affected areas. About 300 BGE crews were working to restore power into the evening. By 11 p.m., about 74,000 customers remained without power.
Forecasters say the region can expect partly cloudy skies today with high temperatures in the mid-80s -- with another chance for showers and thunderstorms.
Sun staff writer Gus G. Sentementes contributed to this article.