Trains to now run until 10 inches has accumulated and the Yellow Line bridge will run regardless of conditions. (http://washingtonexaminer.com/local/dc/2011/11/metro-modifies-plan-snow-season/1962456)
Good move going forward especially since all predictions show that a big-for-DC storm may happen this year and Metro's black eye from the 2010 blizzards is just starting to heal.