Wind slabs, scoured surfaces, and soft snow in the Donner Summit area

Touring up the shoulder of Mt. Judah we found soft snow in sheltered shaded areas. Once we got into more exposed terrain, we could see evidence of wind scouring on the N-NE-E aspects and wind loading on the NW-W-SW aspects. Ski kicks produced shooting cracks in a firm wind slab on a W aspect at 7300 ft. This test slope was low angle and the wind slab would only slide downhill if we undercut the slope. The wind slabs in this area did not extend very far from the ridge and measured between 4 inches and 10 inches in depth. As we continued up to the summit of Mt. Judah we saw more wind scoured surfaces on the exposed upper portions of N-NE-E aspects. Some areas were scoured back to the old rain crust.

Wind scouring had also reduced the size of the cornices looming over those slopes to some degree. Cornices above N-NE-E facing test slopes at lower elevations still broke easily with ski kicks. We did not test the larger ones near the summit because they still remained too large to approach. 

As we descended into more sheltered areas below the summit of Judah, we found soft cold snow with flattened surface hoar on the surface of N-NE-E aspects, thin sun crusts forming on the lower elevation E aspects, and warmer sun affected snow on the SE and S aspects. We did not see any roller balls, pinwheels, or loose wet avalanche activity. Snowpit data, pole probes, and general observations showed continued consolidation in the storm snow and good bonding between the storm snow and the rain crust below it. Ski cuts on test slopes in below treeline terrain mostly did not produce any results except for one small loose dry sluff that entrained the top 4 inches of snow on a 40+ degree test slope.