Uncertainty continues (and will likely continue until we get to Wednesday) regarding the eventual evolution of the pattern late this week into the weekend.
Chances remain pretty low for some scattered snow showers or flurries Thursday night into Friday as the arctic front approaches.
Does a second wave of low pressure develop over the southeast and then move just off the Mid-Atlantic coastline? Or does this feature rush out to sea (zero phasing, progressive jet stream pattern)?
Here is the latest European Ensemble Control model:
Here are the various European Ensembles:
Looking at all 50, as of now there are equal chances of light snow, no snow and a lot of snow.
The Global Ensemble Forecast System (the American built model):
- There hasn’t been a whole lot of consistency with each run of the GFS with last nights 00z showing heavy snow impacting the Mid-Atlantic and this morning’s 06z run showing the system skirting the Tidewater of Virginia with several inches of snow before heading straight out to sea.
We will know a lot more on Wednesday as the pieces of energy responsible for the eventual evolution are better ingested into the models.
DC Storms 
I hope it is just a simple matter of bringing a short wave in the upper atmosphere across the country and having it interact with a cold high pressure system banked up to our north. That is the classic setup for many of our big snowstorms.
The 06Z GFS sheared the trough, giving it a positive tilt and thus squirted the storm out to sea. That has been a commom error over the years and in those cases the heavy snow band ends up further north than forecast. We can hope, anyhow!