New Delhi, Jan. 28 -- A powerful Arctic air mass is driving dangerous winter conditions across much of the United States, bringing lake-effect snow to the Great Lakes, blizzard warnings in Alaska and extreme cold in the Mid-Atlantic, with another storm possible later this week. Schools in Indiana and North Texas remained closed or delayed on Wednesday, citing dangerous wind chills, icy roads and safety concerns even as conditions slowly improved in parts of Texas.

Cold air sweeping across the Great Lakes is producing persistent lake-effect snow through Friday, the National Weather Service Weather Prediction Center (WPC) said in its short-range forecast.

In New York, a lake-effect snow warning remains in effect for Oswego, Jefferson, Lew...