It appears that dividing line will setup across central Maryland today. Areas north of Baltimore will see little to no accumulation while in the counties to the south of the city, a Winter Weather Advisory is in effect for 1-3 inches of snow with the highest amounts the further south you go.
Even further south, A Winter Storm Warning is in effect for far southern Maryland and the Eastern Shore where up to 6 inches of snow may fall.
As for timing, expect a rain/snow mix to continue to develop from south to north, changing to all snow later this afternoon. The snow will continue into tonight before tapering off before midnight.
Skies will clear tomorrow, beginning a stretch of cool and dry conditions through the weekend before it turns sharply colder next week.