A large portion of the nation’s center is in a winter storm watch or warning Monday morning, with snowfall expected to blanket virtually the entire state of Nebraska, eastern South Dakota, southern Minnesota, Iowa, much of Kansas and parts of northwest Missouri. The system will eventually move east, causing some lake-effect snow in the Northeast. The system will deliver freezing rain to Missouri and parts of Iowa as it moves east and unwinds into thunderstorms with some potential to become severe in the southern Plains. A second system could deliver snow from Kansas and Oklahoma east to the southern Corn Belt and Southeast on Friday. A shift in the jet stream resulting from a high-pressure ridge parking over the Arctic is largely responsible for the shift to an active weather pattern in the U.S. this week. See more from the latest forecast.