Two winter storms could snarl Thanksgiving travel - here's what you need to know about flight delays, cancellations, and waivers

• Two major winter storms are threatening to snarl Thanksgiving travel across the US.
• One storm is expected to hit much of the Midwest, while the other targets Northern California and Southern Oregon.
• Air travel is likely to be affected regardless of the storms' exact tracks, and flights across the US could be delayed or cancelled.
• Airlines including American, Alaska, Delta, JetBlue, Frontier, Southwest, Spirit, and United have issued travel waivers letting some affected passengers change their flights without any fees. Scroll down for details on the waivers, and check back here for updates.
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Two major storms are threatening to disrupt millions of people traveling for the Thanksgiving holiday.

The first storm will move through the Rockies, Great Plains, and Great Lakes regions between Monday and Wednesday, leading to winter storm watches across a wide swath of the central US, from Colorado to the Upper Peninsula of Michigan.

"Should the storm develop to its full potential by Wednesday evening and take a northward track toward the Great Lakes, heavy, windswept snow would fall just northwest of the storm's center with heavy rain and perhaps severe thunderstorms to its south and east," said Courtney Travis, a meteorologist with AccuWeather.

The second storm is expected to slam into the West Coast from Northern California to Southern Oregon on Tuesday and lash the area through Thanksgiving. The National Weather Service is already describing the storm as potentially "historic" and "unprecedented."

Both storms are expected to unleash tumultuous and dangerous weather with heavy rain and snow, damaging winds, and possibly thunderstorms.

This year's Thanksgiving travel period is expected to be the busiest since 2005 and a record-breaking number of passengers are expected to travel by air. The two storms have the potential to cause major transit delays across the US

Even in areas far away from the storms, a ripple-effect of delays from other parts of the country could snarl holiday travel plans, as aircraft are repositioned or delayed in other parts of the country due to the weather.

Several airlines have already issued preliminary travel waivers, although we expect to see these expanded as the forecasts become more detailed, and as the storms begin to make an impact.

Even if your flight hasn't been delayed or cancelled yet, you can take advantage of waivers to proactively rebook yourself, making alternate arrangements before it's too late and other flights are all booked up.