Started our tour from Mutal Dell around 0830 this morning under a ground cloud layer and temps in the teens. Passing through 8000', we got above the clouds and it was clear, with temps in the low teens, and a light breeze. Above 10,000', winds were out of the N in the 20-40mph range. Moving above 9000' we encountered a very stout and variable wind slab that was widespread. This windslab varied in thickness between 1-10cm and showed no propagation. It sat upon a fist hard layer around 15-30cm deep. The base of the snowpack was knife hard and had an unknown depth. Many hand tests and ski cuts (and a heard of mountain goats) showed no reactivity in the windslab. The cornices in this area are getting big. The one above The Grunge is massive. We stayed far back from ridgelines.