Mt Shasta Avalanche Center - Shasta/Trinity Nat'l Forest

First above treeline observation/pit since atmospheric river event/January storm cycle. Overall snow surface very smooth with isolated sastrugi wind erosional features. Fairly uniform surface hardness, soft mostly with hard slabs and packed powder throughout terrain. Skiers and snowmobilers riding similar slopes. Windy, NE, blowing snow onto westerly slopes. Chilly today but sunny! Unknown total height of snow, couldn't hit ground! A lot of wind loading but no recent avalanches. Observations and tests looking at wind slab stability. Danger perceived as moderate.

Above 8000ft, the snowpack remained dry and was not affected by the 01/08 rain event. The wet snow that fell at this elevation on 01/08 now exists as a supportable 6cm thick MFcr. Height of new snow since 01/06 is 51cm.

At this location the 12/23 FXxr layer exists without a MFcr.

Past 48 hour northwest wind event created a scoured snowpack consisting of all forms of snow surfaces: breakable crust, hard slabs, wind buff, soft powder, icy crusts, protruding sastrugi features and old ski/snowmobile tracks. 12/23 persistent weak layer still present just below crust (21cm) with Q1 shears in small column tests, however ECT test could not produce propagation. Total HS: 231cm

MFcr/FCxr at old snow new snow interface. New storm snow was very unconsolidated and was not yet showing slab characteristics.

Crown Profile. HS-NS-R3-D3. The avalanche likely occurred between the afternoon of 12/16 and the early morning of 12/17. The width of the avalanche was 1500ft, the vertical run was 2000ft, and the crown height ranged from 1-6ft. Debris was 10-20ft deep minimum. The majority of the avalanche involved recent wind deposited snow. In a rocky, 150 foot section of the crown where this crown profile was conducted, the avalanche stepped down and failed on a much deeper layer of old snow.