That storm triggered a Tornado Warning in northern Virginia. that has since expired.
Here's the radar loop from Sterling.
Forecasters say they expect the worst of the storm threats will be out of the region by "mid-afternoon" as the cold front passes by.
Stream flooding and road closures in Maryland are already being reported from Antietam Creek in Leitersburg, Washington County. More flooding is reported from Emmitsburg, in northern Frederick County; also in Libertytown, Cavetown, Ballenger Creek. Trees are reported down in Barnesville and Bealesville, in Montgomery County.