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

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.

Pit dug adjacent to recent wind slab avalanche that occurred sometime during recent storm. Period of high avalanche danger very short lived. Warm storm followed by cool temps and wind has created a nicely consolidated layer of homogenous new snow capped by 1-2 cm temp crust. Total height of snowpack: 190 cm. / Height of new snow: 48 cm / Height of pit dug: 95cm (down to old snow, rock solid)

Good stability. No fractures in small column tests. Rain runnels visible on snow surface.

Layer of concern was a density break within the storm snow. Easy failures with SC results in small column tests, but no propagation in large column tests possibly due to the slab thickness (15-20cm). The recent storm has created an upside down hardness configuration in the top 15-20cm due to a warming trend throughout the storm. Freezing rain in the afternoon has capped the new snow of with a 4F hard zipper crust on all aspects up to 8000ft+

Quick Pit....Stability very good in this area. Uniform density and isothermal snowpack. Could not clearly identify any layers of concern at this point. No recent or past avy debris visible. Cold temps. Some areas hosting small surface hoar. Cold and clear nights to come could cause further surface hoar growth. Not an issue now until we get more snow on top, maybe our next weak layer. No concerns at this point. Rime ice on trees and rocks along ridge lines.

Above treeline continues to remain heavily wind affected and firm... strong NW winds persisted today with visible blowing snow. Cold temps/high winds sublimating snow prevented any significant wind slab build up above TL. Near and below treeline, variable conditions continue. Only shady and protected aspects, mostly NW/N/NE hold soft snow. Otherwise, a variable thickness breakable surface crust exists on most southerly aspects.