When Punxsutawney Phil popped up and saw his shadow on Feb. 2, a collective groan rippled across the Eastern United States, where freezing temperatures, ice and snow have cast a big chill for days.

Now, it's got its own catchphrase: the polar vortex, which could be making a return engagement to the U.S. later this month or in January. Or maybe it won't. Regardless, the polar vortex – everyone's ...