More than 200 million people were under an advisory or warning on Friday, the National Weather Service said. The weather service’s map “depicts one of the greatest extents of winter weather warnings and advisories ever,” forecasters said. The Tennessee Valley Authority, the nation’s largest public utility, ended its rolling blackouts Friday afternoon but continued to urge homes and businesses to conserve power. The weather service is forecasting the coldest Christmas in more than two decades in Philadelphia, where school officials shifted classes online Friday. It was so bad in Vermont that Amtrak canceled service for the day, and nonessential state offices were closing early.
