Sorry for not getting a picture, it was dark on my way back to Brighton and it didn't show up on the camera. Looks like a snowmobiler was sidehilling when a steep convex roll avalanched.

It looked to me (total speculation as I did not look at it up close) that it ran on an old sun crust. It was a small avalanche but had a decent debris pile that could of knocked you over or perhaps rolled you a time or two.