Lenticular clouds often form near mountains. The air has to flow up and over the mountain, creating a train of successive standing waves. The air oscillates up and down as it moves past the mountain. (Just like a mega flute, really.)
In this case, no clouds formed on the primary wave as the air passed over the mountain. But on the first wave back up, a massive UFO-like cloud formation appears. This is a classic “stack of plates” lenticular cloud. As the air oscillates, it stacks new ‘plates’ below the existing plates.
You can see a ‘short stack’ of two plates to the left of the UFO; that is a tertiary wave.
For more examples, look here.
For a nice diagram of the process, look here.
A panorama of three photos taken with at 150mm lens at f/8 on the Phase One camera. ISO 50, 1/1000th second exposures.