North of the city the land flattens and the sky turns enormous, so storms announce themselves an hour ahead, a gray wall sliding down from Wyoming. Northglenn Snow Removal is staged for that arrival, plowing drives and lots, shoveling walks and steps, clearing entries and treating ice across the north metro. The five o'clock run along the frontage roads happens while the interstate is still nothing but headlights and blowing powder. By the time the commute thickens, the properties are open and the walks are down to concrete. Quiet work, finished before most people learn there was anything to do.