Special Weather Statement issued January 7 at 6:32PM EST by NWS Baltimore MD/Washington DC

Motorists and those walking outdoors should use caution tonight as
black ice is likely in some areas. Any water that is still
present on roadways and sidewalks will quickly turn to ice as
temperatures drop well below freezing.

Be prepared for black ice on some roads. Slow down and use
caution while driving. If you are going outside, watch your first
few steps taken on stairs, sidewalks, and driveways. These
surfaces could be icy and slippery, increasing your risk of a fall
and injury.