Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Zack Wentz
Observation Date:
November 21, 2020
Submitted:
November 21, 2020
Zone or Region:
West South
Activity:
Skiing/Snowboarding
Location:
Crystal - East Peak & Upper Cement Basin

Triggered Avalanches

Did you trigger any avalanches? 
Yes
Was it intentional? 
Yes
Avalanche Type:
Soft Slab
Size:
Size 1: Relatively harmless to people
Elevation:
5700ft
Aspect:
SE
Comments:
Lower section of East Peak in a shallow area amongst rocks & cliff bands. Upper 10cms of storm snow slid on the 11/16 rain crust, which was widespread but significantly more stiff and supportive on solar aspects. Start zone slope angle: 40 degrees. Slide slid for approx. 20 ft and stopped. Crown depth: 10cms. Crown width: 20 ft.

Signs of Unstable Snow

None reported

Observations

Avalanche Obs: Sa sz1 via ski cut on a 40 degree SE facing slope at TL. Storm snow slid on 11/16 rain crust.

Snowpack Obs:
-Solar aspects below 6,000ft. Significant sun crust forming on surface over old 11/16 rain crust. Above 6,000ft: 11/16 rain crust is widespread on these aspects and supportive. 15-20cms of F- faceted storm snow sits above this crust.

-Polar aspects: 35cms of faceted storm snow sits atop the 11/16 rain crust. 3-4mm surface hoar was observed on the surface in sheltered areas @ TL.

-Polar aspects in wind-loaded areas: 55cms of faceted storm snow and wind-transported snow sits atop the 11/16 rain crust. Wind-loaded snow was slightly stiffer than polar aspects without wind-affect, but was generally quite soft (F+).

Didn’t do any instability tests and didn’t observe below the 11/16 rain crust, which was widespread and very supportive.

Weather Obs:
-Sky: Clear
-Wind: Calm
-Blowing snow: Nil

Media

Advanced Observations

Observed Avalanche Problem #1: 
Dry Loose
Comments: 
Widespread loose, unconsolidated faceted storm snow on all aspects & elevations. Significantly more new snow on sheltered aspects above TL (15-20cms on solar aspects, 35-40cms on polars, and 55cms in wind-loaded areas).
Observed Avalanche Problem #2: 
Storm Slab
Comments: 
Small soft slabs are possible on solar aspects around shallow features (cliff bands, rocks, etc).
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