When I saw this I thought lenticular clouds and it wasn't until I scrolled down and saw Sally's comment. She is the queen of recognising cloud formations.
@Weezilou This is really what I saw Louise, it is almost sooc. A few weeks back I posted a series of similar clouds. We seem to get them regularly hanging over the mountains this time of the year. ;-)
Again, amazing! I recall studying the many types of clouds back in a high school class, but I've never (ever) seen the likes of this...not even over mountains or mesas (flat topped mountains)! It's so curious to me, I'm going to look them up to see if I can find more information...SO Fascinating!