A winter storm is set to sweep across America on Wednesday and into Thursday, bringing a mixture of sleet, snow, freezing rain and possible flooding to the Plains, the Northeast, the Midwest and the Mid-Atlantic. More than 117 million people are under a winter weather watch, warning, or advisory, and nearly 20 million in the Southeast are facing potential flooding. The wintry mix will likely be the result of warm, moist air from the Gulf of Mexico combining with a colder storm system leaving the Rockies Tuesday night into Wednesday morning. Flood and flash-flood watches will extend from northern Alabama and Mississippi northward to West Virginia, CNN reports, with 2 to 4 inches of rain likely to fall across the region. Memphis and Nashville will see even higher amounts of rain, with 5 to 7 inches expected through the end of the week.