Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Zack Wentz
Observation Date:
February 13, 2021
Submitted:
February 15, 2021
Zone or Region:
Snoqualmie Pass
Activity:
Skiing/Snowboarding
Location:
Roaring Ridge - Christmas Tree Bowl

Triggered Avalanches

Did you trigger any avalanches? 
Yes
Was it intentional? 
No
Avalanche Type:
Soft Slab
Size:
Size 1: Relatively harmless to people
Elevation:
Below treeline
Aspect:
N
Comments:
Numerous size 1 soft storm slabs on steep, unsupported features at and below treeline.

Signs of Unstable Snow

None reported

Observations

Avalanche Obs: See above.

Snowpack obs: Our goal for this day was to investigate the depth and reactivity of the deep persistent slab problems, the 1/13 FC/MFcr and 2/1 FC/MFcr. We dug a full profile in an opening below treeline (limited travel based on deep snow, new wind, and travel time), and the results are listed below. Note: below the most recent storm snow, there is a pretty stout, and thick rain crust, and identifying the 1/13 and 2/1 layers were fairly difficult in this location. We identified these layers using changes in relative hardness on our obs wall, though IDing these layers in this location was difficult. We did a PST on a weak layer of rounding facets, which I presume is the 2/1 FC/MFcr, that was sandwiched between the stout ice crusts. The PST results are shown below in the attached Snow Pilot profile.

Weather Obs: Cloudy and cold. S-1. L-M winds from the East.

Media

Profile showing instability tests performed on the weak interfaces

Advanced Observations

Observed Avalanche Problem #1: 
Storm Slab
Comments: 
Observed Location:
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