Look! Up in the sky! It's a lenticular cloud! This was just a couple miles south of Ellensburg.
Lenticular clouds typically form downwind of mountain ranges and Ellensburg is east of the Cascades. Fear not, Flatlanders, they do occasionally form without the aid of topographic relief. There just needs to be a standing wave. Air flowing over a mountain range will often produce standing waves, as shown in this highly technical illustration, but the waves can also form via other means. If you're lucky the edges of a lenticular cloud will be irridescent. Here's lots of pretty pictures.