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On Friday, November 3rd, the front range of the Rockies experienced classic lenticular clouds as a result of Trapped Lee Waves. We've gathered data, images, and some insight to help you explore and understand the mountain weather behind the phenomena.

This is a lenticular cloud over the Boldmethod Office in Boulder, Colorado. It's formed by the mountains behind it, but they can extend hundreds of miles downwind.

Lenticular clouds form as air moves over mountain peaks, created by a localized area of cresting and crashing air currents.

Lenticular clouds are typically found just above mountain peak height all the way up to 15,000 feet above peak height, downwind of the mountain range. In order to form a trapped lee wave with lenticular clouds, you need 3 things:

1) Cross-barrier winds of at least 20 knots

2) Moderately stable atmosphere

3) Shear Ratio Greater than 1.6

The shear ratio is a way to compare the winds above the mountain peaks, to the winds at mountain peak height. Today the winds at peak height (12,000 ft. MSL) are 19 knots, and the winds at 6,000 feet above peak height are 33 knots, the shear ratio is 1.7 (33 / 19 = 1.73), and the likelihood of a lenticular cloud forming increases.