Ocelot Brewing in Dulles. I would get their scotch ale. Thick, strong, spiced, and can be drank warm oddly enough. I would get smashed on growlers of it 5 years back. I haven't lived in VA in that time but I would wager Ocelot still makes a good beer.

Edit: I know it's not a stout or porter but it was a beer I enjoyed in cold weather and thought it could be worth sharing.