ATLANTA. Snow blanketed a vast swath of the Deep South on Friday, triggering a flurry of winter weather warnings that closed businesses and schools, canceled hundreds of flights and caused traffic gridlock. It also unleashed a flurry of snowman construction and sledding in places more accustomed to sunshine than snow. The storm dropped a rare coating of snow as far south as Brownsville, Texas - near the border of Mexico - up through southern Louisiana and parts of Mississippi, Alabama, Georgia and the southern Appalachians. "This is an unusual event - to see snow falling this early in the season...