The National Weather Service has issued a flash flood warning until 8:30 p.m. on Friday, June 1, for southeastern Montgomery County, Washington, DC, and other counties in suburban DC.

"Excessive runoff from heavy rainfall will cause flooding of small creeks and streams...urban areas...highways...streets and underpasses as well as other drainage areas and [low-lying] spots," according to the National Weather service advisory. 

A flash flood watch is in effect until midnight for much of Maryland and the DC region, the advisory adds.

Across the region, thunderstorms producing 1 to 2 inches of rainfall are expected, with isolated rainfall amounts of over 4 inches, according to the advisory. 

A tornado watch is also in effect in Montgomery County, DC and surrounding areas until 9 p.m., according to a National Weather Service advisory.

Along with the tornadoes, there could be hail of up to 1.5 inches in diameter, wind gusts up to 70 mph and dangerous lightening, the advisory adds.

This is a "volatile, dangerous situation for the mid-Atlantic as a strong, dynamic cold front sweeps through the region this evening. A combination of instability and spin in the atmosphere mean development of violent thunderstorms with damaging winds, large hail and tornadoes are possible," the Capital Weather Gang reported.