A nor'easter comes up off the Sound after midnight and Mount Vernon goes quiet underneath it. That is when JC Snow Management is loudest — plow down, spreader running, working the shared driveways and the narrow alleys behind the brick two-families where a wide truck has to be patient. Clearing here is a game of inches: the apron, the walk, the one spot the plow pile must not go. By the time the sky turns from black to slate, cars are moving and the block gets its morning back. That is the entire point of the night.