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Observation: Short Swing

Observation Date
1/18/2024
Observer Name
Gagne & Lambrose & BC 101 Students
Region
Salt Lake » Big Cottonwood Canyon » Mill D North » Short Swing
Location Name or Route
Mill D North - Short Swing
Weather
Sky
Scattered
Wind Direction
Southwest
Wind Speed
Light
Weather Comments
Gusty winds at the canyon bottoms in the morning, but winds diminished by late morning. Overcast to obscured skies cleared early afternoon to partly-sunny.
Snow Characteristics
New Snow Depth
12"
New Snow Density
Medium
Snow Surface Conditions
Powder
Damp
Snow Characteristics Comments
Shady aspects held dry powder, but the mid-January sun crusted south and southwest aspects.
Red Flags
Red Flags
Recent Avalanches
Wind Loading
Poor Snowpack Structure
Red Flags Comments
Widespread avalanche activity on Wednesday, January 17, including wind-loading at the mid and upper elevations from west/southwest winds. Poor snowpack structure with PWL buried 75 - 150 cms down.
Avalanche Problem #1
Problem
Persistent Weak Layer
Trend
Same
Problem #1 Comments
The PWL is becoming more stubborn to trigger, but the poor structure is evident and it is down 75-150 cms with a 4F/1F slab on top of fist-hard facets. On a west aspect at 8,100' we got ECPT21, failing down 90 cms on a layer of facets. With ~1" of water weight from the Wednesday storm, the PWL is stressed again.
Everyone in our group agreed they would not travel on a steep slope (> 30°) given the PWL issue.
Snow Profile
Aspect
West
Elevation
8,100'
Comments
Traveled with a great group of BC 101 students into the terrain south of Short Swing in mid Big Cottonwood Canyon. (Photo below is just a few of the 16 students.) We were able to look at all aspects and traveled up to 8,200'.
Key observations:
- No cracking or collapsing.
- Although we got clean shears at the interface between the new and old snow, instabilities with the 30 cms of storm snow on Wednesday have settled out.
- Widespread rollerballs on steep, southerly aspects at mid elevations.
- South and southwest aspects will be crusted Friday morning.
- PWL is still a concern with ECTP21 failing down 90 cms on buried PWL.
Given the poor snowpack structure, we all felt it is still not time to step out into steep avalanche terrain.
Thanks to UAC partner Uinta Brewing for sponsoring today's BC 101 class with the UAC!
Most of the crowns that were visible Sunday and Monday on Mt Raymond and Gobbler's Knob are now filled in with storm and wind-blown snow.
Today's Observed Danger Rating
Considerable
Tomorrows Estimated Danger Rating
Considerable
Coordinates