Announced layoffs soared in January from a 13-year low in December, led by job cuts from retailers who saw weak holiday sales, according to data released Thursday by outplacement consultancy Challenger, Gray & Christmas. Total layoffs announced last month rose to more than 45,000, up from about 31,000 in December and 40,000 in January 2013. "The post-holiday job-letting in the [retail] sector was inevitable," said Chief Executive John Challenge