In the coming weeks, pilots can expect to see mountain waves in several snowy, mountainous regions. When wind flow is perpendicular to a mountain, as the wind velocity and altitude increase during an inversion below 15,000 feet, or a stable air mass layer aloft, mountain waves will occur. These atmospheric disturbances are characterized by lenticular clouds that alert pilots to their potentially deadly presence. It’s possible to predict mountain waves and other atmospheric disturbances with a high level of accuracy, though, giving pilots a chance to decide whether or not to fly under such conditions.