The National Weather Service has issued a Severe Thunderstorm Watch for the D.C. area through midnight tonight (Thursday). A line of rain and strong storms are slowly approaching from the west.

From Arlington Alerts:

The National Weather Service has issued a Severe Thunderstorm Watch for all of the Metro Area, effective until 12 midnight. The current most likely time of thunderstorm arrival is between 7:30 and 9:15 PM. Storms are moving east at 15 mph with reported 60 mph wind gusts.