Northwest Avalanche Center

Observation: Public

All Observations

Observation Details

Name:
Ben
Observation Date:
November 15, 2020
Submitted:
November 15, 2020
Zone or Region:
Snoqualmie Pass
Activity:
Skiing/Snowboarding
Location:
Alpental in closed resort

Triggered Avalanches

Did you trigger any avalanches? 
Yes
Was it intentional? 
No
Avalanche Type:
Soft Slab
Size:
Size 1: Relatively harmless to people
Elevation:
1550M
Aspect:
SW
Comments:
Our party of three started touring up from the main Alpental parking lot at 8am in the rain. Rain turned to snow shortly after leaving the base area. We followed a skin track up to the top to Armstrong Quad. A skin track continued up into Breakover trees. We left that skin track and toured up towards the bottom of Edelweiss Bowl. We continued to tour up towards the guntower, staying on the rib above Edelweiss bowl and lookers left of the Chair 2 lift line. We toured over small convexities to test stability and did not see cracking or signs of instability. At around 1550M, the rib separating us from steeper terrain ended and we traversed below a rock band. Skier 1, breaking trail triggered, what appeared to be a small slide, starting ahead and above just below the rock band. The slide then propagated back along the rock line. Skier 1 was hit by the slide, knocked over and dragged approximately 5 feet. Skier 2 , took a few steps back and was not in the slide. Skier 3 was also not hit by the slide. Skier 1 was partially buried, but was able to easily let skiers 2 and 3 know that he was ok and had all of his equipment. Skiers 2 and 3 helped him out of the snow, but this did not require shovels. This slide was fairly small. Approximately 50 feet wide and 1ft deep. Ran around 50 vertical feet. Size 1. Upon turning around to descend, we saw a crown in what I believe is Rollen bowl. That slide propagated interminably all the way down the ridge towards Shot 6. We do not know whether this much larger slide was connected to the original, smaller slide we triggered. However, the larger slide was not there as we toured up shortly before. The larger slide was 1 to 2 feet deep and ran between 100-200 vertical feet. This slide was quite wide, approximately 500 ft, but broken up by terrain features. We descended the rib relatively close to our skin track to the base of chair 2. We then did a second lap up the guntower, but stayed below our previous highpoint.

Signs of Unstable Snow

None reported

Observations

See above incident description.

Media

Looking further south down the ridge.  If you look closely you can see crowns continue down the ridge below the rock bands.
Looking up where we triggered the avalanche
Looking down from where we triggered the avalanche
Looking back around the corner from where we trigger the avalanche
Looking up at the largest part of the slide, from around 30 feet back from where we triggered the smaller slide.
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