Gunnison

We remotely triggered two large persistent slabs on windloaded slopes near treeline, facing N and NE. We did not see any natural activity in this basin.

cloud cover: few; wind loading: previous; recent snowfall (cm): 15 to 20; snow avail for transport: moderate amounts

In wind sheltered terrain above 10,000', slabs were 45 to 50 cm thick (F to 4F) over well-developed facets and depth hoar layers (F hard).  The Christmas rain crust separating these layers is thinner than what I've seen in areas like Schuylkill Ridge - about 2 -3 cm on shady aspects at 10,000' and thins out by 10,700'.  Collapses appeared to be failing just below the crust.  On windloaded slopes NTL, slabs were 100 to 120cm thick (up to 1F), and failed on the 11/30 depth hoar layer on the ground.  At those locations, the Christmas facet layer was 4F and rounding.  . Collapsing increased in frequency and loudness as we gained elevation. Collapsing and cracking began around 10,000' with soft collapses that radiated 20 to 50 feet, and evolved to large, booming collapses in wind loaded terrain above 11,500'.