Whumping, Cracking, and Shattered Slopes on Silver Peak

Widespread whumphing, cracking and collapsing occurred in the near and below treeline terrain between 7000' and 8000' on the N-NE aspects. Some of the collapses traveled quite far, and in several cases shooting cracks "spider-webbed" across entire low angle slopes. These cracks, whumphs, and other failures occurred as the layer of weak sugary snow grains (facets formed before the storm) collapsed under the combined weight of the new snow (18-22 inches of low density, cold snow) and a person. In some areas enough anchors (stumps, bushes, logs, trees, rocks, etc.) existed to prevent the collapses from traveling too far. Of course these same barely covered anchors also prevented people from traveling easily in those areas.

In addition to the persistent weak layer problem noted today, we observed wind slabs had formed and were continuing to form on the exposed near and above treeline N-NE slopes.

We did not investigate these wind slabs or any other avalanche prone slopes closely because of the numerous signs of instability, the known presence of a widespread persistent weak layer, and the distance that fractures could propagate through the buried weak layer. We also avoided low angle terrain connected to those slopes and chose to travel in low angle terrain or slopes that did not have snow cover previous to this storm for these same reasons.

Photos: N facing low angle slopes in below treeline terrain that "shattered" under the weight of a skier.