Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Zack Wentz
Observation Date:
December 2, 2020
Submitted:
December 3, 2020
Zone or Region:
West South
Activity:
Skiing/Snowboarding
Location:
Crystal Backcountry - Henskin Lake Area

Triggered Avalanches

Did you trigger any avalanches? 
Yes
Was it intentional? 
No
Avalanche Type:
Soft Slab
Size:
Size 1: Relatively harmless to people
Elevation:
6,000ft
Aspect:
NW
Comments:
Small, isolated wind slab was triggered on a 40 degree convex roll in an open area at treeline. The failure was down 6-7cms on the 11/30 interface.

Signs of Unstable Snow

None reported

Observations

Avalanche Obs: See above.

Snowpack Obs: Performed a few hand shears in wind-loaded snow at treeline. All hand shears were stubborn (showed resistant fracture character) and failed on the 11/30 interface. Density of the wind slab ranged from 4F+ to 1F depending on location and degree of wind-effect.

Weather Obs: In the AM, observed moderate-strong W winds & moderate blowing snow (snow was being transported via saltation). PM obs were limited, but blowing snow was observed at ridgetop.

-Zack Wentz

Advanced Observations

Observed Avalanche Problem #1: 
Wind Slab
Comments: 
Observed Location: Widespread wind slab was observed on all aspects in the treeline and alpine elevation bands.
Potential Size: Based on depth of the slab, likely up to sz2
Likelihood of triggering: Possible; likely in more wind-loaded features such as immediately below ridgetop or in cross-loaded gullies
Layer Depth & Date: Wind-deposited snow varied in depth, ranging from 5cms thick-25cms thick all sitting atop the 11/30 interface.
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