Observation: Mid Canyon Big Cottonwood

Observation Date
3/3/2024
Observer Name
Gagne
Region
Salt Lake » Big Cottonwood Canyon » Mid Canyon Big Cottonwood
Location Name or Route
Mill D North - Beartrap - Reynolds
Weather
Sky
Overcast
Precipitation
Light Snowfall
Wind Direction
Southwest
Wind Speed
Moderate
Weather Comments
Sustained moderate winds from the southwest getting well down in canyon bottoms and creating wind drifts across all elevations.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Medium
Snow Surface Conditions
Powder
Wind Crust
Snow Characteristics Comments
Widespread wind-affected snow with slopes that were scoured or drifted. Non wind-affected slopes had ~30 cms of dense storm snow with some graupel mixed in.
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Avalanche Problem #1
Problem
Wind Drifted Snow
Trend
Same
Problem #1 Comments
I was getting cracking in fresh wind drifts in the morning, but even though drifting continued into the afternoon, the wind drifts became less reactive and wouldn't crack. The sustained winds created drifts primarily on slopes with an easterly aspect, but there was plenty of cross-loading so drifts could be found on any aspect.
The winds were erratic at times, and some slopes had scouring down to an old, frozen crust while a short distance away there would be a 30-45 cm thick fresh wind slab, so it was difficult to find a pattern other than slopes facing north through southeast seemed to have the majority of wind-loading.
With winds forecasted to remain moderate to strong, the problem will persist.
Snow Profile
Aspect
East
Elevation
9,100'
Comments
Overall I was finding conditions more stable than expected given how much wind-drifting was occurring. Other than some minor cracking in fresh wind drifts in the morning, most wind slabs were unreactive. The new snow and wind drifts were well-bonded to the old snow surface, and I only noticed graupel within the storm snow, but other observations from today mentioned graupel was acting as a weak layer.
In the photo below, you can clearly see the March 1 "Dust Crust" from the strong pre-frontal winds and we'll see this layer for the rest of the winter. I was getting clean shears in a thin layer of decomposing fragments just below the dust layer, but pit scores were poor-quality ECTN that crumbled in the storm snow. I do not expect this layer below the dust crust to be a problem going forward.
Many exposed slopes facing southwest were scoured from strong pre-frontal winds Friday and Saturday.
Today's Observed Danger Rating
Moderate
Tomorrows Estimated Danger Rating
None
Coordinates