Boletín de aludes

West Slopes Central

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Surfaces will harden overnight, but intense sun will soften steep slopes on the southern half of the compass. If you time it right, you may find just a little softening aiding in less chattery, maybe even nice, travel. Wait too long and you could sink in several inches, making for unpleasant travel and an increase in wet avalanche danger.

Problemas de aludes

  • Loose Wet

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

    Surfaces will start firm on Saturday, but steep, south-facing terrain will soften quickly in the sun. Avalanches could run from steep, rocky areas. You could also trigger an avalanche if the snow softens enough on a steep, south-facing slope.  

    As the sun softens surfaces, pay attention to how far you’re sinking into the snow. Notice rollerballs coming down steep slopes. If you start sinking in to your ankles, steer clear of steep, south-facing slopes. Move to northerly aspects or stay on slopes less than 35 degrees and avoid travelling beneath steeper locations. If you’re chasing good spring conditions you might be able to continue slowly shifting your aspect as the sun moves, maintaining travel on slightly softened surfaces.

    (2/11/2022) One small wet loose (point release) avalanche was seen Friday, originating in a very steep, south-facing rocky area  at about 4400ft in the West North zone, similar to what we're seeing in the West Central zone. Photo: Sierra Bishop

  • Persistent Slabs

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

    The persistent weak layer may have survived on upper elevation slopes which didn’t see as much moisture in the snowpack over the last few days. Buried 1-2 feet below the surface and found just above the Late January Crust, we saw occasional avalanches on this weak layer. They usually occurred in isolated pockets on north-facing slopes, with an uneven distribution on a slope-wide scale. 

    Until we know more, assume this problem still exists on upper elevation terrain on the northerly half of the compass. If there are several inches of a solid surface freeze, you probably will not trigger an avalanche on this layer. However, if you find areas with a minimal surface crust at upper elevations, the weak layer may still exist. So far, we’ve found that you can get away with traveling on many steep slopes without causing an avalanche, but there is a very small chance that you could trigger an avalanche on that layer if you find just the right spot on the slope. It’s important to consider this if you’re planning on heading to steep upper elevation northerly terrain.

    (2/7/2022) This persistent weak layer was obvious before the warm, wet weather. It may have broken down at this elevation, but it may still be present in above treeline areas. Photo: Irene Henninger

Avalanche Discussion

Warm, springlike weather oftentimes leads to cornice failures. Consider avoiding slopes beneath them, and stay back from their edges, as always. This springy weather also means you’ll probably encounter very hard snow surfaces, which are especially a challenge in steep terrain. Prepare for these firm conditions if you head into the backcountry on Saturday.

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