Talk about being in the right place at the right time.
Elton Hyland had a camera handy in Kapowsin when Mt. Rainier put on a show for the ages last fall.
What you are seeing is a stacked version of lenticular clouds near the mountain. While the flat, alien-like clouds are not all that unusual around here getting the conditions right for what looks like a stack of pancake clouds is a little unusual. (Although remember this big event in 2009?)
And this is the first time I've had a good video and time lapse of an event:
The cloud is formed when you have three ingredients: Warm, moist air that is just on the cusp of saturation, laminar flow (when you have winds constant with height -- as in little to no turbulence or shear) and something big to get in the way, like, say, the region's tallest mountain.
When the air flows over the mountain, it will create waves downstream where the air is now going up and down, and up, and down -- like ripples on a pond or waves on the ocean. When the air goes up, it cools a little bit and when conditions are on the cusp of saturation, that slight cooling is enough to create a cloud. When the air sinks back down again, an opposite drying effect occurs and the cloud disappears.
While to us it might look like the clouds are floating in place, in fact, the air is streaming through the cloud as it hovers there -- the cloud is just showcasing the right spot in the atmosphere where the air is undergoing its lift and sink. Sometimes this occurs right over the summit, giving the mountain a hat. Other times, it's just downstream as in this case.
To get the "stack of pancakes" look, you have this effect happening at multiple layers. Watch closely in the video and you can see times where layers disappear and then magically reappear.
To locals, the clouds are a sign that rain is on the way -- usually within 24 hours. That's because that needed moist air with laminar flow usually occurs in the hours preceding a weather system. Think of it as Rainier unfurling its umbrella! :)