I am sticking with the map I posted yesterday afternoon:

The Models have come into agreement that the heaviest snow accumulations (those possibly going over a half of a foot) should be across northern Maryland along the interstate 70 corridor into the Baltimore Area. I still think a general 2 to 4″ of snow looks reasonable for the immediate DC Metro Area. Temperatures are trending a bit colder tonight and wet bulb temperatures are as well (dew points). Translate: The rush hour on Tuesday is looking like hell. The snow should continue to fall for much of the day on Tuesday except for areas from Fredericksburg over to southern Maryland where a dry slot will likely move in, cutting down on accumulations there.