Nor'easters arrive here with the wind shoving up Mountain Avenue toward the Berkeley Heights line, and by midnight the road is one long unbroken white. Heights Associates is out in it, plowing drives, clearing walks and steps, and treating the ice that sets in behind the storm. Snow in New Providence rarely falls all at once; it comes in waves, and the four-in-the-morning pass matters as much as the first one did. The measure of a night's work is a household that wakes, opens the door and finds nothing in the way. That is the entire point of it, and it never stops being satisfying.