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Observation: Big Cottonwood Canyon

Observation Date
12/23/2021
Observer Name
Gagne/Heilweil/Singleton
Region
Salt Lake » Big Cottonwood Canyon
Location Name or Route
Spruces -> Little Water -> Big Water - Butler Exit
Weather
Sky
Overcast
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Moderate to strong gusts along exposed ridges. Winds were getting down lower into drainages. 0C at 9200' Despite the moderate to strong winds, we were not seeing much wind-loading and this may have been because the fetch - the southerly slopes - was crusted and there wasn't much available snow for transport.
Snow Characteristics
Snow Surface Conditions
Wind Crust
Melt-Freeze Crust
Damp
Snow Characteristics Comments
Snow surface has been worked from warm temperatures and winds. The good news is that I was finding faceted snow and depth hoar on the snow surface earlier this week, but warmth and winds have eroded weaknesses at the snow surface. Surfaces on all aspects up to 9,000' were damp. This will be helpful as the current snow surface is unlikely to act as a persistent weak layer with additional storm snow.
Red Flags
Red Flags
Poor Snowpack Structure
Red Flags Comments
Comments below.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Increasing Danger
Problem #1 Comments
Very poor snowpack structure found along BCC/MCC ridgeline between Little and Big Water. Height of snow is < 1 meter, and closer to 45-60 cms below 9500' on northerly aspects. 20-45 cms on southerly aspects.
We only had one collapse today, but pit results all yielded full propagation with extended column tests and quick tests would get a 30 cm column of snow to fail upon isolation.
Weakest snow is the layer of facets underneath storm snow since 12/9.
Trend is for increasing danger with storm snow and wind-blown snow in the forecast. The 15-30 cm layer of weak snow at the ground on aspects facing northwest through east will likely be quickly overloaded with upcoming storms.
Comments
Snowpack discussion from newly-minted Level 2 Avalanche Course graduate Vic Heilweil.
Video
Video of ECTP6 illustrating poor snowpack structure.
Video
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
High