Blue Mountain

The skier-triggered avalanche on an east-facing slope of Blue Mountain likely failed in a thin (1 inch +/-) 4F hard layer of decomposing fragments + near-surface facets. This layer sits above the March 9 crust. The faceted grains were generally 1 mm in size or smaller. The portion of the slab above the weak layer of concern is a 1F hard slab that trends right-side-up toward the surface to F- (last nights approx. 4 inch surprise storm). We observed CT RP 19 x 2 at the failure interface, and ECTN 21. In the ECT, the crack propagated 1/2 way across the column. An easy shovel insert behind and the slab quickly slid off. We also observed east to moderate PC failures in CTs in upper storm layers and an ECTN5. Below the March 9 crust is a weaker layer of faceted grains + rounding facets, and this layer was 1F- hardness. No cracking or collapsing on the same slope and the height of snow at the crown was approx. 250 cm.