A storm pounding California's Sierra Nevada mountains with snow Tuesday was taking aim at the Colorado Rockies and could roll east and slam the Appalachians on Thanksgiving Day, bringing unsettling travel weather to millions of Americans hitting the skies and roads for the holiday weekend.

Mother Nature is about to serve up some unappetizing conditions for the millions of Thanksgiving travelers: sloppy weather, snow, the coldest temperatures since February and a potentially disruptive storm are on the way through the holiday weekend. Here’s a day-by-day look at what to expect this week.