Deep and Shallow in Ophir Creek

We wanted to see an area similar to the terrain where the human-triggered persistent slab avalanche in the Mt. Rose Wilderness occurred. From the report, we surmised that it must have happened in an area with a shallower snowpack. We thought that we might be able to find similar snowpack conditions in the Ophir Creek area. As we skinned out Chickadee Ridge, we saw numerous settlement cones around the trees indicating consolidation in the snowpack. We also noticed that we did not sink very deep into the snow while breaking trail. Ascending to the high point on the ridge, we found lots of evidence of wind transport in the form of drifts and pillows of wind-blown snow and a few cornices. We did not see any signs of instability on these wind features. 

We traversed out the ridge to an area the was E-NE-N facing with some open trees between 7800 ft and 9000 ft similar to the terrain described in the avalanche report and started probing to look for places with a more shallow snowpack. The first snowpit we dug was over 2m deep and tests in this pit did not show any lingering signs of instability. So we kept looking. We finally found an open N facing slope at 8100 ft where the Dec 11 facets were closer to the surface. In this area the snowpack was very shallow (only about 45cm deep) before the Jan 26-28 storm. We dug another snowpit here and got unstable compression test results on the Dec 11 facet layer. In this area, the layer was not continuous and we did not find any other signs of instability. Areas with a similar shallow snowpack and a more continuous weak layer like the place where the avalanche was reported would still be problematic.