Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Josh Hirshberg
Observation Date:
March 28, 2021
Submitted:
March 28, 2021
Zone or Region:
Stevens Pass
Activity:
Skiing/Snowboarding
Location:
Tunnel Creek

Triggered Avalanches

Did you trigger any avalanches? 
Yes
Was it intentional? 
No
Avalanche Type:
Dry Loose (Sluff)
Size:
Size 1: Relatively harmless to people
Elevation:
5,400
Aspect:
SE
Comments:
Triggered a handful of very shallow (3cm) sluffs in the new snow on steep solar slopes w smooth old crusts.
Photo:

Signs of Unstable Snow

None reported

Observations

Terrain: Hollywood Bowl in Tunnel Creek via Stevens Pass ski area.

Weather: Overcast skies, moderate W winds w light blowing snow, light snowfall becoming moderate (S1) by 12:00. Accumulation was 3cm at 13:00. Snow, wind, and avalanche hazard increased after I left the field.

Snowpack: Surfaces were partially frozen. Boot pen varied from 0-30cm. I dug a profile at ESE, 5,400ft in Tunnel Creek. Notable layers: The upper 40cm is a sandwich of multiple semi-frozen crusts and moist melt forms w the most recent wetting front down 40cm. Moist, weak (4F hard) melt forms down 70cm. The Jan 24th facets are 1F hard, showing sintering, and down 216cm with K- hard and P+ hard adjacent layers. See the graph and photo below for more details.

Media

Profile graph from ESE, 5,400ft in Tunnel Creek. Notable: the most recent wetting front down 40cm, Wet, weak melt forms down 70cm, and the Jan 24th facets down 216cm.
Shallow drifts up to 20cm at Gemini Pass, SW, 5,000ft.
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