Bollettino valanghe

Stevens Pass

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

The possibility of very large and deadly avalanches exists, which is keeping the danger elevated. Avoid traveling on steep, large open slopes, or any runouts beneath those slopes, even at below treeline elevations.  

Problemi valanghivi

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    3–4

    Very large and unsurvivable avalanches could still occur, so maintain a conservative mindset as you travel in the backcountry. There is a lot of uncertainty around when and why these avalanches are happening, however they continue to surprise us with alarming regularity. For this reason, avoid going into, or underneath open or sparsely treed terrain with large start zones above you. Keep maintaining awareness of the terrain you are in, and add a large margin between where you travel and where these avalanches may run.  

    A persistent weak layer of facets near a crust that was buried mid-January has caused several avalanches for over a month now. Elevations above 5000ft on east, south, and west aspects lie our biggest concern. We've seen avalanches running up to size D4, over 1500ft wide, and at least 10 feet deep as recently as March 1st. As the days pass confidence grows on the possibility of the layer becoming dormant, but it is too soon to jump to that conclusion. There were two reports of cornice falls on Wednesday, one involving a party which luckily walked away uninjured. The last few days of warmer weather elevated our concerns for cornice failure that could, in turn, trigger deep slab avalanches. Temperatures cooled slightly since Friday but continue to avoid slopes with overhead cornices, and do not travel anywhere near the edge of one. The slopes beneath those ticking time bombs are the ones that are most likely to fail with a trigger as large as a cornice fall. 

    (3/1/2021) A very large avalanche (D2.5) was triggered by WSDOT highway forecasters on March 1st in a portion of the West Camp path on Rock Mtn. Adjacent sections of this avalanche path ran naturally on Feb 26th. Photo: WSDOT

Avalanche Discussion

Reports of impressive deep slab avalanches failing on the mid January weak layer continue to trickle in. On Monday, WSDOT avalanche teams triggered an 8ft deep D3 avalanche on the southeast face of Rock Mountain east of Stevens Pass, along with several D2 soft slab and wet loose avalanches. In the Chiwaukum Mountains, a natural D3.5 avalanche in upper-elevation north-facing terrain is suspected to have run on Sunday. A massive avalanche (D4) ran naturally in the West Camp path on Rock Mountain last Friday night. Also last Friday, a partial burial occurred on the edge of the Stevens Pass Ski Area boundary, with the avalanche running on a storm interface.

Given the bounty of uncertainty at play with avalanche conditions, forecasters remain concerned about the potential for very large avalanches. We're in a prolonged period of historically unstable conditions and dealing with a weak layer that has challenged even seasoned professionals. The deep slab problem continues to pose high consequences and demands conservative terrain and travel choices from all of us. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home

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