We can take the deeper discussion to the banter thread, but the fall line in DC only scrapes the far northwest part. Once you get pass east from the Nebraska - Colorado Ave corridor you're on the coastal plain.
The wet bulb temp is 30° in Gaithersburg according to the wx station at work. The RWIS site on I-495 at the American Legion bridge has a wet bulb of 31°.
Reminds me of the sneaky Wednesday evening event in 2016 that iced things up before the weekend snowstorm. Everyone was focused on the impending big snow and the roads were an ice rink from a coating of snow.
Seems as though there has been an uptick in lighter returns on the radar over the past 30 min or so. Even a fewer heavier echoes showing up across northern Carroll, Baltimore and Harford counties.
If we somehow manage a solid event Tuesday then temps could be interesting post front. Fresh snowpack and air mass can yield interesting temperature departures.