A cross-country storm, a blast of Arctic air and an outbreak of showers and thunderstorms are threatening to snarl traffic and pile up delays at airports over the Thanksgiving holiday weekend, one of the nation's busiest travel periods.

With Thanksgiving holiday travel well underway, many have reached their destinations — but for everyone else, a storm tracking from the Rockies to the Midwest and Northeast into tomorrow will bring rain and snow,

Winter storm warnings have been issued for parts of the U.S. this Thanksgiving week—here's where snow could fall.