A winter storm headed for southern Minnesota could bring more than a half-foot of snow or more. The National Weather Service says snow is expected to begin over southern Minnesota by late afternoon Thursday, and reach central Minnesota by Thursday night. That snowfall is expected to continue throughout much of Friday, with amounts over 6 inches possible by Friday afternoon. The greatest accumulations appear to be most likely along Interstate 90 in south-central and southwestern Minnesota. A winter storm watch is in effect from late Thursday afternoon through Friday.