Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

It may still be possible to trigger avalanches near ridgelines where strong winds deposited snow into deep slabs during the recent storm. The base of cliffs, ridgelines with little vegetation, and alpine bowls at high elevations are the most likely areas to trigger these avalanches. If the snow feels stiff or sounds hollow, stick to lower angle routes or terrain sheltered from the wind.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Winds associated with the recent storm averaged in the mid-20mph range with gusts up to 32mph. While storm totals underdelivered, winds still built deep slabs on lee aspects. Winds may have deposited snow onto slick crusts and other variable older snow surfaces. These variable surfaces lead to uncertainty about how easy they will be to trigger. With increased uncertainty, it is important to approach new terrain slowly and observe changing conditions as you gain elevation. You can use quick hand pits or your probe/ski pole to feel for stiffer layers of snow over softer layers. Snow that feels stiff, hollow, or cracks shooting away from your feet or equipment are signs you should use low angle routes or move to terrain sheltered from the wind. 

     

    (12/8/2021)

    An example of long shooting cracks in freshly wind drifted snow, a red flag sign of instability. 

    Photo: Matt Primomo

Avalanche Discussion

It's early season, the snowpack is shallow, and early season hazards exist, such as shallowly buried trees, rocks, and other obstacles. These may now lurk just below the new snow and can increase the consequences of even a small avalanche. 

Expect frigid temperatures for Monday, with highs in the mid-teens. Bring and wear extra layers and monitor exposed skin for cold injuries. Consider using a buff or face mask to protect your nose and mouth from wind chill. 

We have limited observations on the extent and distribution of weak, faceted snow from mid-November. An Observer noted being able to easily push a pole through the snowpack to the ground in the Hairpin Valley on the 22nd, indicating a weak snowpack. On the 25th, observers found light rain up to Blue Lake Col. The rain had created a few very small wet loose avalanches, and about an inch of the snow surface was saturated. The warm temperatures and rain may not have been enough to strengthen this weak layer of snow. We hoped the recent storm would be a test for this weak layer of snow, but the lackluster precipitation totals may not have been enough to push this layer over the threshold to produce avalanches. Approach sheltered northern terrain slowly and dig down below the storm snow to identify any sugary, weak snow. Avoid steep slopes if you find this layer or feel the snowpack collapse. 

If you are out and about in the mountains, let us know what you find by submitting an observation.

Regioni coperte