OMAHA, Neb.—A major winter storm dumped more than a foot of snow on parts of the middle of the country while another system blanketed parts of the Southwest with snow, disrupting travel for a second consecutive day Tuesday and shuttering many schools. There were closures of several coronavirus testing sites on Monday and Tuesday in Nebraska and Iowa, and both states saw 12 to 15 inches of snow in places. At least 4 inches of snow was expected through Tuesday across most of an area stretching from central Kansas northeast to Chicago and southern Michigan. National Weather Service meteorologist Taylor Nicolaisen, who is based near Omaha, Nebraska, said up to 15 inches was reported in spots between York, Nebraska, and Des Moines, Iowa. He said it’s uncommon for the region to get more than a foot of snow from a single storm, and it has been decades since some cities …