Boletín de aludes

East Slopes North

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You can trigger avalanches in the recent storm snow at middle and upper elevations. These will mostly be wet loose avalanches, though you may encounter drier recent snow on shaded slopes. Weak sun may still warm the recent snow, up to 10", that accumulated this weekend.

Problemas de aludes

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    You can trigger wet avalanches on slopes steeper than 35 degrees, especially above 6,000ft. Watch for signs of instability, like fresh avalanches and rollerballs, that indicate you could trigger an avalanche. Anticipate the chances of triggering avalanches and move to lower-angle slopes to avoid them.

    If you travel to upper-elevation terrain, you'll find dry snow on shaded, northerly aspects. Be ready to assess for other new recent snow instabilities, like loose dry or wind slab avalanches.

    (3/24/2024)

    Skiers triggered small wet avalanches in 20cm (8") of new storm snow on steep, sun-exposed slopes. 

    Kangaroo Pass, SSE, 6,600ft

    Photo: Will Govus

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5

    Until we can be more certain about the snowpack structure, continue to put a large buffer between where you travel and large, complex, and unsupported start zones at upper elevations.

    While triggering avalanches on deeper weak layers may be difficult, it's not out of the question. If you travel on northerly slopes at upper elevations, use snowpack tests to look for weak layers in the middle of the snowpack, 3-4 feet below the surface. These may show up as strong-over-weak layers or very thin, soft interfaces adjacent to a crust. 

    (3/15/2024)

    This crown from Azurite Peak highlights the type of big, alpine terrain where the potential for very large human-triggered or cornice-triggered avalanches remains.

    Photo: Willie Webster

Avalanche Discussion

A spring storm delivered about 8-10" of snow by Sunday morning. The sun warmed the snow on sun-exposed slopes. Observers reported triggering small wet avalanches in the recent snow on southerly slopes at mid and upper elevations.

Following a week of very warm weather, temperatures have cooled. A refreezing upper snowpack (at least at middle and upper elevations) has minimized snowpack concerns for avalanches occurring below the surface snow. However, the new storm snow will accentuate hazards on aspects that stayed colder throughout the recent warmup. That said, we have a lot of uncertainty about the snowpack structure as observations are limited. Be prepared to make your own assessments of the persistent slab problem. On sun-exposed slopes, you may find a new host of layers created by water pooling in the upper snowpack. As these freeze, they should be adding strength to the snowpack. Elsewhere, a few older weak layers to look for include:

-The March 9th strong-over-weak interface 1-2 feet below the surface.

-2-4 feet below the surface, you can find the Feb 25th and mid-February weak layers along with the Jan 31st crust within 1 foot of eachother.

Lower elevations and sun-exposed aspects may be significantly melted back. Prepare for rocks, stumps, and frozen avalanche debris that may be shallowly covered by fresh snow or fully exposed.

Snowpack information is limited outside of the Highway 20 corridor and Harts Pass. Let us know what you find if you get out into the backcountry!

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