Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

Wed
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Expect wet loose avalanches to occur on sunny slopes on Tuesday. Monitor the snow surface and when it begins getting moist and rollerballs start coming down, retreat to shady aspects. Start with small test slopes and thoroughly investigate the bonding in the new snow layers before exposing yourself to steep upper elevation slopes on Tuesday where slab avalanches are possible.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Wet loose avalanches will slide naturally as sunny slopes warm on Tuesday.  Keep an eye out for rollerballs or pinwheels rolling down steep slopes, especially in areas with rock bands. As the snow moistens, retreat to shady aspects or lower angle terrain. Avoid traveling under steep terrain with wet slopes above you.

    Human triggered wet loose avalanches are likely in steep terrain. Stay aware of your sluffs which may entrain more snow and surprise you from behind as you travel downslope. 

    An example of a wet loose avalanche which ran from nearby a cliff band earlier this year. Expect to see ones like this and larger on Tuesday. Photo: Zach McGill

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Several natural and human triggered slab avalanches occurred on Sunday night and Monday. Most avalanches failed beneath the new snow layer- 6-12" deep. Snow was most reactive in steep wind loaded areas, although the wind loading was subtle and slabs remained very soft. Many avalanches appeared more like storm slabs, just requiring slopes in the upper 30 degrees or steeper to slide. 

    Tuesday slab avalanches will remain possible to trigger on steep slopes, especially where wind loaded. You may find them more reactive on shady or leeward slopes. Use small test slopes to determine how readily the recent snow layers slide before exposing yourself to larger slopes. Although they are most likely to fail on the Sunday night interface, over the weekend avalanches were reported failing in the storm layers since the 18th, now buried around 3 feet deep.  Failures that deep are not out of the question. Make sure to enter steep slopes from the top where snow would break below you, rather than travelling in from midway on a slope where snow could slide down from above you. Until thoroughly tested, avoid steep slopes at higher elevations.

    (3/22/2021) This D2 slab avalanche occurred naturally sometime near the end of the storm 3/21-22. Table Mountain, 5400ft, Northeast aspect. (Corner Pocket). Photo: Adam U

Avalanche Discussion

Over 3 feet of snow was recorded at the Heather Meadows weather station from 3/18 - 3/22. Our avalanche problems are limited to surface layers, but thise is a substantial amount of new snow. Be sure to investigate these recent layers before committing to steep slopes, as we have seen several slab avalanches running in these layers, and now wet loose avalanches are a concern as well. 

Cornices are continuing to increase in size and weight. They could drop onto slopes below acting as huge triggers. Stand back from cornices along ridgelines and minimize overhead exposure to these features. Several large glide cracks and a few glide avalanches were observed recently as well. Cooling temperatures should limit glide activity for now, but these avalanches are difficult to predict. If you notice crevasse-like cracks in the snowpack, avoid slopes beneath those features.

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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