Observation: Big Cottonwood Canyon

Observation Date
12/5/2020
Observer Name
B
Region
Salt Lake » Big Cottonwood Canyon
Location Name or Route
Upper Big Cottonwood Canyon
Weather
Sky
Clear
Wind Direction
Southeast
Wind Speed
Calm
Weather Comments
Temperatures moderated from the below average figures that we were experiencing earlier in the week, with mild afternoon temperatures at 8500 feet hitting the upper 30's.
Snow Characteristics
Snow Surface Conditions
Faceted Loose
Melt-Freeze Crust
Damp
Snow Characteristics Comments
As noted by others for weeks now, variable conditions continue to exist with a mixture of riding conditions. Fortunately we found mostly supportable conditions that allowed for a few decent turns in the 5 cm of loose NSF's on low angle northerly facing terrain. M/F crust continue to grow on the lower half of the compass, and slick/slide for life conditions exist on steep southerly aspects where there is still any snow left.
Red Flags
Red Flags
Collapsing
Poor Snowpack Structure
Red Flags Comments
While traveling through Moderate angled terrain on a Northerly aspect at 8800 feet we experienced collapsing. Snow pit results at 8850, NNE, slope angle 23 degrees, HS: 40 cm, indicated a multiple layering of Crust/Facet sandwiches. The collapse we experienced appeared to be a result of the a failure in upper most layer of Crust/Facet below the Crust at 31 cm. Of Note: there was also a 5 cm layer of NSF's in this location.
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Decreasing Danger
Problem #1 Comments
We did not travel in any upper elevation exposed terrain, but recent observations of cracking and collapsing in small pockets of wind slab indicate this may still be an isolated concern.
Avalanche Problem #2
Problem
Persistent Weak Layer
Trend
Same
Problem #2 Comments
See above for poor snowpack structure with areas of loose weak snow on the surface, and in very steep terrain on the upper half of the compass one might be able to trigger a loose dry sluff that could push them into unfriendly terrain. It will definitely be interesting when we get the next significant load; and travel between then and now may continue to help us identify not only the variable potential connected weak slopes out there, but more importantly, the potential areas with no or very limited snow that may offer some safe riding during these coming times.
Obviously the main danger is the early season low snowpack conditions with rocks, stumps and downed trees.
Today's Observed Danger Rating
Low
Tomorrows Estimated Danger Rating
Low