A major winter storm " the season's most extreme so far " is set to lash the eastern half of the United States with damaging ice and heavy snow late this week. It's all being fed by a brutal blast of Arctic air that's bringing the season's coldest air to date. "An expansive winter storm will produce a swath of heavy snow, sleet and freezing rain from the Southern Rockies/Plains and Mid-South starting Friday and shifting toward the East Coast through Sunday," the Weather Prediction Center warned Tuesday morning.