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

A snow storm is racing from the Rockies to the Midwest, impacting airports from Denver, Colorado, to St. Louis, Missouri. On Thanksgiving, heavy rain is expected to move to the East Coast, bringing rainy I-95 conditions from Florida to Maine.

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.