Some evidence of wind slabs and storm slabs on Andesite Peak.

We arrived on Donner Summit at 8:30 am to the very end of snowfall. Rapid clearing occurred around 9 am as the storm cleared. Shortly thereafter, the wind shifted to the N but remained light to moderate speed. Around 5 inches of new snow was in this area. Lots of snow was available for future wind transport in this area on all aspects with increasing wind speed.

Breaking trail we had some minor cracking around our skis indicative of storm slab instability. A quick look showed large graupel from the start of the storm, sitting on top of the newly buried rain crust. Hand pits showed the cracks going down to this graupel layer.

Moving up to treeline and wind exposed terrain, we encountered some wind slabs in predictable locations below cornice features. Wind drifted snow was up to 18 inches deep where these wind slabs existed. Our ski cuts on a steep test slope intentionally produced two D1 wind slab avalanches about 10 feet wide and without much propagation. A look at the crown showed a soft F hard slab on top of a denser 1F+ hard slab. This density change was mid height within the newly drifted snow and where the two D1 avalanches had failed in the snowpack. In this location, wind drifted snow was fairly well bonded to the rain crust below, unlike in the wind protected areas we had traveled below treeline.

As skies cleared, cloud cover was less than forecast and allowed for some very minor snow surface warming to become apparent by 10:00 am. Air temperatures were still below freezing with no signs of snow melting off of trees. Some increasing density of the storm snow could be felt on solar aspects, but roller balls were minimal at best up to our departure from the area around 11 am.