The DC area gets a "good" snow storm (≥6") about every 2 or 3 years. Typical behavior is to get a snow day the day of the storm and often the day after as well. Anyone trying to go anywhere during the storm is likely to have a rough time--the local streets won't see anything like a plow come through for a good long while, so it's not really sane to attempt to go anywhere. Even for smaller storms, only 1-2" total, shutting down completely for the day is pretty typical.