The groundhog saw its shadow on Sunday, signaling six more weeks of winter in Chicago—and this week’s forecast proves it! Chicago started the workweek with unseasonably warm weather, reaching a high of 49 degrees on Monday, according to the National Weather Service. But don’t get too comfortable—the warmth won’t last. Temperatures are set to plunge below freezing overnight. Tuesday will bring a sharp cooldown, with a high of just 30 degrees and wind gusts up to 20 mph…