Today DC shut down (including Metrobus service) in response to four inches of snow
I do understand the value of anticipatory planning.
Given that MBTA estimates that it will take them a month without snow to dig out and clear all of the snow blockages--they are paying people $30/hour to dig out railroad tracks--it's easier to open back up if you do a measured shutdown.
But the reality is for the most part, the DC area doesn't get hit all that hard by snow. The two back-to-back snowstorms in February 2010 were an exception.
And one of the competitive advantages of a city--excepting snow on the level of a Montreal normally ("Montreal does great job ridding itself of snow - but it takes time and costs a fortune," Attleboro Sun Chronicle) or Boston this year (Minneapolis gets hit badly as well)--is being able to get around despite snow and other adverse weather conditions because of the mobility efficiencies produced by proximity and density.
Also see "A "maintenance of way" agenda for the walking and transit city."
Photo of a graffiti-ed MBTA system map ("Boston Mess Transit") from Facebook.