For perspective, the average December snowfall at IAD, DCA, and BWI is: 3.5", 3.0", and 2.3" respectively. A lot of folks are going to get their December average snowfall in under 6 hours and there's still two weeks left in the month.
Sterling WFO is releasing a special 18z balloon. It'll be worth checking when it's posted on SPC's page, especially for the lower Susquehanna Valley crew that's worried about mixing.
It's snowing a solid clip in Reisterstown. So long as it's not washed away this evening I'll be happy. Snow on Christmas decorations is like double secret bonus snow.
HRRR is colder and a bit SE with the surface low. It still has DCA as frozen at 2:00 pm today. That's a good benchmark to see how well it's handling things.