Low pressure over the southern Plains is forecast to deepen as it heads northeast toward the Ohio valley on Sunday. In advance of this system, winter storm watches and warnings have been posted from the central plains, eastward across portions of the Midwest. Snow is expected to be ongoing Sunday morning as close to Chicago as west central Illinois and eastern Iowa. The snow area is then forecast to work northward, eventually overspreading the city by early afternoon. Though heaviest snow will likely occur across central portions of Illinois and Indiana, prolonged wind flow across lake Michigan may inflate totals over portions of northeast Illinois and northwest Indiana. Accumulating snow is expected to exit the Chicago area late Sunday evening, but snow showers are forecast to continue into Monday.