Millions of Americans flying or getting behind the wheel for the Thanksgiving holiday are bracing for flight delays and dangerous roads as bad weather sweeps the US in what’s forecast to be a record-breaking travel period.

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.

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

Parts of New York, Vermont, New Hampshire and Maine are under winter storm warnings, and precipitation is expected to begin as early as 1 a.m. on Thanksgiving Day. Higher elevations, including area ski resorts, will see snowfall that could continue through 1 a.m. on Black Friday.

Forecasters have warned of another round of winter weather that could complicate travel around the Thanksgiving holiday.

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 messy spell of winter weather continued to dominate forecasts Wednesday across the United States, with a mix of rain and snow expected to materialize in different areas around the upcoming Thanksgiving holiday.