Thousands of frustrated Texans shivered in their homes Thursday after more than a day without power, including many in the state capital, as an icy winter storm that has been blamed for at least 10 traffic deaths lingered across much of the southern U.S. A warming trend was expected to bring some relief later Thursday — just in time for an Arctic front to drop from Canada and threaten northern states, and in particular those in New England, with the coldest weather in decades.