Boletín de aludes

East Slopes North

Northwest Avalanche Center
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Peligro de aludes

Fri
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You can trigger avalanches near and above treeline where recent wind has drifted thick slabs of snow. Use caution on slopes steeper than 35 degrees that have thickly pillowed or wind-sculpted features. You may encounter small wet avalanches on steep southeast through southwest slopes.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    You can trigger large avalanches on leeward, wind-loaded slopes near and above treeline. Cornices, wind features, and firm wind-stiffened snow are all signs that the wind has drifted snow. Watch for signs that you could trigger an avalanche like cracks shooting through the snow and other recent avalanches. Steer around convex roll-overs or thickly drifted features on slopes steeper than 35 degrees. Cornices have become large. Make sure to keep your distance by staying off of them and don't linger under them. 

    From the 1st to the 5th southwest winds blew strong enough to drift snow and form slabs. More recent snow may have covered over the stiff slabs. Use a probe or pole to feel for stiffer snow under soft surfaces. 

    (11/22/2020) An example of cornices hanging over a leeward slope , earlier this season. Photo: Josh Hirshberg

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1

    Watch for small wet avalanches on steep, sunny slopes near and below treeline. There may be enough sun to warm sun-exposed southeast through southwest aspects. Watch for surfaces becoming moist, and roller-balls, and tree-bombs as signs of warming. If you see this, move off of slopes steeper than 35 degrees before they become wet and weak. Watch for natural wet loose avalanches coming from overhead rocky terrain.

    (11/22/2020) An example of loose wet avalanches near Stevens Pass from earlier in the season. Photo: Josh Hirshberg

Avalanche Discussion

You can find a big difference in the snow and avalanche conditions as you move through the zone. Near Washington Pass and even as far east as Delancey Ridge, most of the snowpack is strong and avalanche concerns are limited to snow that has recently fallen and built the uppermost layers. However, in the eastern part of the zone, you may be able to trigger a dangerous persistent slab avalanche. In areas like the Winthrop foothills, the Twisp River and Lost River drainages, and areas east of Mazama the snowpack may be shallow and weak. Observers have reported signs of instability like whumping collapses and older weak layers of snow underlying the recent storm snow. In these areas, you may encounter similar conditions to those in the Wenatchee Mountains. If you're venturing into these eastern mountains, expect a weaker more dangerous snowpack, use extra caution near avalanche terrain, and be prepared to make your own snowpack assessments. 

Deep snow immersion is also a concern that could be life-threatening. Be vigilant around tree wells and stay close to a partner while traveling through the trees. 

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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