Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Thu
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 trigger slab avalanches near and above treeline in areas of wind-drifted snow. Small loose avalanches are possible at lower elevations and in wind-sheltered terrain. More dangerous conditions may exist near the borders of other forecast zones.

Problemi valanghivi

  • Wind Slabs

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

    You could trigger wind slab avalanches on leeward sides of ridges and on cross-loaded terrain features at upper elevations. Avalanches may be bigger and more likely at the highest elevations. Pay attention to signs of wind transported snow and recent drifting as the day goes on and as you climb onto higher slopes. Take note of which aspects are drifted from the wind and notice how that may change as you move through the terrain.  Blowing snow, stiff, firm snow surfaces, and cracks shooting through the snow are all signs that you could trigger a slide. You can avoid these avalanches by sticking to sheltered terrain, traveling on slopes under 35 degrees, or choosing slopes where the wind isn't drifting fresh slabs of snow. 

    (2/11/2021) An example of cracks shooting through the snow in wind-exposed terrain on Thursday near Stevens Pass. This is a warning sign that you could trigger a wind slab avalanche. Photo: Josh Hirshberg

  • Loose Dry

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

    The sun may trigger loose avalanches on steep sun-exposed slopes. You can trigger them on slopes 40 degrees and steeper where you find light, soft snow on the surface. Dry Loose avalanches can be dangerous if they catch you unaware. Pay attention to any moving snow around you and avoid steep slopes near terrain traps where an avalanche could push you off of a cliff, into trees, or bury you in a gully.

Avalanche Discussion

About a foot of light snow can be found on the surface that fell since Friday. On Monday, observers triggered a shallow avalanche in freshly wind-drifted snow on a northwest aspect above treeline. On Saturday, observers noted many loose snow avalanches in steep gullies at the Goat Wall. On Friday, observers found isolated wind slabs with shooting cracks in alpine locations near Silver Star.

While persistent slab avalanches are unlikely, they're still on our minds in outlying parts of the zone west of Washington Pass and in the eastern mountains. Audible whumphing collapses, cracks shooting through the snow, and widely propagating avalanches are all warning signs. The last persistent slab avalanche occurred near Rainy Pass on the 8th (see photo below). It is suspected to have run on the mid-January crust-facet layer about 2-3ft below the snow surface. On the 9th, an observer on Whistler Mountain reported sudden and propagating test results on the mid-January weak layer on a west aspect at 6,000ft as well as on a NW aspect at 6,600ft. This weak layer has been more shallowly buried and more problematic west of Washington Pass, as well as in the far eastern mountains of the Twisp River and Chewuch drainages.  We have little recent information in these parts of the zone.

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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