Mountain waves can be a hazard all winter, even when you're hundreds of miles downwind of a mountain range. Here's why...

1) The jet stream moves south.

In order for a mountain wave to form, you need strong winds aloft, and wind shear from the mountain peaks to roughly 6,000' above the peaks.

In the summer months, the jet stream is located further north along the Canadian border. But as winter approaches, the jet stream makes its way south, flowing across the major mountain ranges of the US, from the Sierra Nevada to the Appalachians.

2) There's more cross-barrier flow.

The strength of mountain waves depends on a few factors, one being cross-barrier flow. When winds aloft strike a mountain ridge at a 90-degree angle, it generates stronger mountain waves.

3) Increased air stability.

The more stable the air, the more likely it is to produce a mountain wave. And in the winter, the US tends to have a lot of stable air.

As an air parcel is lifted over a mountain ridge, it expands and cools making it denser than the air around it. As this lifted air crosses the ridge of a mountain, it starts to descend along the backside of the range, attempting to reach equilibrium. Due to the momentum, it overshoots the equilibrium point and compresses, resulting in the air parcel heating up. This makes the air parcel more buoyant, causing it to rise back toward the equilibrium point. This oscillation creates waves over and over again for hundreds of miles.

Have you experienced mountain wave? Tell us about your experience in the comments below!

Take the next step.

Have you ever felt uncomfortable flying in or around the mountains? We have. That's why we built our Mountain Weather online course.

Whether you're flying on the East Coast, the Coastal Ranges of California, or any of the rough terrain in between, Boldmethod's Mountain Weather course make you confident and comfortable flying around the mountains.

You'll learn how to evaluate mountain weather during your planning and while you're in flight. You'll also learn how terrain generates updrafts, downdrafts, turbulence, and storms, and changes the direction of the wind throughout the day.

Plus, for less than the cost of a cross-country flight, you get lifetime access to tools that increase your confidence and make your flights more fun.

Ready to get started? Click here to purchase Mountain Weather now.