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 through 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,

A powerful winter storm packing heavy snow, rain and even severe weather is threatening Thanksgiving travel plans for millions as people across the U.S. leave home ahead of the holiday to celebrate with friends and family.