A major winter storm sweeping much of the U.S. is producing heavy snow and ice as it threatens areas from the Ohio Valley to the Mid-Atlantic— leaving tens of millions under weather alerts Monday.The big picture: The multi-day storm that's partially tied to the polar vortex prompted governors in Arkansas,

Winter storm warnings have been declared from Illinois to New Jersey. And some areas will get a lot of snow. They will also get freezing rain and ice, blustery winds and frigid temperatures.