A nor'easter announces itself over North Weymouth hours in advance: the sky turns the color of pewter, the gulls come inland, and Bicknell Square empties out by supper. Plowguys of Weymouth are fueled and hooked up before it starts. The night is driveways, stairs and walkways, salt spread at the bottom of the slopes where tires lose their grip, then the whole route run again as the wind fills everything back in. Snow removal is measured by exactly one thing — whether a car can get out in the morning. Around these streets it usually can.