Temperatures near 50 degrees over the weekend sabotaged the snow sculpture of a “top secret” vault guarded by laser beams, part of the “License to Chill” espionage theme of winter carnival. But lots of students lined up for the polar bear swim at Occom Pond and enjoyed the return of Nordic and Alpine racing at Oak Hill and the skiway. And others took part in snowshoe and human dog-sled racing, as well.