A powerful US winter storm spread a paralysing mix of heavy snow, sleet and freezing rain from the Ohio Valley and mid-South to New England on Sunday, compounded by bitter, Arctic cold gripping much of the nation east of the Rockies. Winter storm warnings were posted for most of the eastern third of the United States covering 118 million people, as the deep freeze strained energy supplies in some areas, and the National Weather Service predicted widespread, prolonged travel disruptions. An...