A swirling mass of thunderstorms moved southeast across Maryland last night, bringing down power lines and trees, and dropping hail in some spots. Despite warnings, no tornadoes were reported.
Lightning struck a home in the Parkton area about 5:40 p.m. and a Brooklyn house about five minutes later, fire officials said, but no injuries were reported.
About 5,500 BGE customers were without power about 9 p.m., with as many as 1,000 out in Essex and Elkridge.
The National Weather Service issued the first tornado warnings for Harford and Baltimore counties just before 5 p.m., when Doppler radar indicated rotation in the approaching thunderstorm.
The spinning cloud formations moved from several miles north of Monkton, in northern Baltimore County, southwest toward Reisterstown, Owings Mills and Randallstown, just west of Baltimore.
Hailstones just under an inch in diameter were reported in Owings Mills and Northern Virginia during the storm, and dime-size to quarter-inch hail fell in Greenbelt. The tornado warnings expired at 6 p.m.
The storm's movement - from northeast to southwest - is unusual for this area at this time of year, but the pattern has persisted all week.
Meteorologists said it has been driven in part by a stalled storm system lingering off the northeastern coast of the United States. The counter-clockwise circulation around the storm has kept the region under a flow of cool, moist maritime air from the east or northeast.
At the same time, the clockwise rotation of a high-pressure system over Ontario has added a flow of warm, dry air south toward the Middle Atlantic states..
The collision of the two rivers of air formed a front, "and right now that front is right on top of the Baltimore-Washington area," said Todd Miner, a meteorologist with Penn State Weather Communications in State College.
For now, the cool, maritime air will dominate, Miner said. "It will feel quite cool [today], with temperatures only reaching the 60s. It will be mostly cloudy, with light showers. But the thunderstorms are over."
Another warm-up is due, with highs near 90 degrees for Father's Day.
Sun reporters Liz F. Kay, Laura McCandlish and Nick Shields contributed to this article.