Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

You can still trigger large avalanches in wind drifted snow, primarily on convex features steeper than 35 degrees near and above treeline. Use visual clues to identify and avoid wind loaded slopes, and seek out lower-angled and wind-sheltered terrain to reduce your risk. Pay attention to changing conditions when the sun comes out Monday. Solar radiation may cause loose snow avalanches on steep sun-exposed slopes.

Problemi valanghivi

  • Wind Slabs

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

    Areas of wind drifted snow will become more sensitive to triggers as you climb up in elevation. The most dangerous conditions will exist in leeward terrain high in the alpine. Be especially cautious of convexities, gullies, areas around rocky outcrops, and slopes below cornices. Slabs could break 1-2ft feet thick and the slick 12/21 crust below could act as a good sliding surface for avalanches. Feel for sudden changes in snow surface texture and hardness as good indicators of the wind slab presence. Previously wind drifted slabs may lurk underneath a few inches of more recent low-density snow, making them more challenging to identify. Ease into terrain slowly and carefully evaluate the snowpack as you travel. When in doubt, default to lower angled terrain. 

    (12/27/2020) A large avalanche (D2) remotely triggered by a skier broke 1-2ft deep on a north aspect around 5200ft in the backcountry outside of the Mt. Baker Ski Area. This avalanche is adjacent to the same slope where another skier triggered and was partially buried in an avalanche on 12/16. Photo: Adam U

  • Loose Wet

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

    Keep a close eye on steep, rocky, sun-exposed slopes where solar radiation may be strong enough to destabilize snow surfaces and create small loose avalanches. Watch for rollerballs and pinwheels as evidence snow surfaces are becoming wet and weak. Snow shedding from trees and rocks may initiate loose avalanches in steep terrain below. Minimize your exposure to slopes greater than 35 degrees in direct sunlight and move to shaded terrain to avoid the problem. Loose snow sluffs could even trigger slab avalanches as they run downslope.

     

    Example photo of rollerballs and pinwheels

Avalanche Discussion

Several triggered avalanches were reported Sunday in the Mt. Baker area. Avalanches failed 1-2ft deep within new and wind drifted snow in northerly mid to upper elevation terrain. Some avalanches grew large (D2) breaking over 100ft wide. Skies stayed cloudy with light snowfall through most of the day limiting observations in the alpine. Storm totals since Christmas are around 2ft throughout the West North Zone in areas above 4000ft. The recent snow is wind affected in exposed terrain and inter-storm layers are still settling and stabilizing. 

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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