Observations from Castle Valley and Andesite

Our group was on an observation day during an AIARE 1 with Tahoe Mountain School. We toured around Castle Valley and Andesite Peak, during our tour we found mostly consistant conditions while travelling through below treeline and near treeline terrain. Significan surface hoar growth was noted through most areas of depression, such as the meadows and creek beds, although we didnt believe this to be a problem in the future.

Our group did experience some whumphing and collapsing sporadically throughout the day, but mostly in sheltered areas, not so much on more broad open slopes. We searched for test slopes where old wind slabs and persistent slabs might lurk. None of our test slopes produced any signs of instability, although when slabs were isolated and unsupported we were able to have small areas propagate and fail.

We decided to dig a pit on a NW aspect near Castle Pass with the goal of targeting the Dec 11 facets. We found HS ranging from 90-105, with a ski pen of 20cm and boot pen of close to 80cm and a slight wind skin on the snow surface. Our pits revealed easily identified 40-45cm of total new storm snow from last week, 2 distinct crusts and the Dec 11 facets. The facets were still well developed and multiple CT's all had consistent results with sudden colapse's within moderate taps. Facets ranged from 1-1.5mm, and although they still maintained the typical characteristics of extremely weak and sugary grains, closer examination revealed the sharp corners of some grains are beginning to round. 

We did have multiple interesting results during both shovel tilt and compressions tests on the 12/17 storm snow. Multiple CTE's and easy releases on tilts tests were witnessed on the 12/17 - 12/13 interface, we initially thought it was just storm snow instabilities, but a quick glisten in the sun showed small feathery grains. They were not very big or distinct, but present in the location we were digging. It wouldnt be out of the box to see some development last week during the clear weather, whether this was an isolated area with some preserved grain or more wide spread we are not sure.