Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

You are most likely to trigger an avalanche in steep wind-loaded terrain at upper elevations, especially on shady aspects. Pay attention to changes in snow depth and firmness of surfaces as you travel. Transition to lower angle terrain if you find thicker, wind-affected slabs of snow.

Problemas de aludes

  • Wind Slabs

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

    A large wind slab avalanche was remotely triggered on the Shuksan Arm in the Baker backcountry Sunday afternoon. You can read the observation HERE. Other wind slab avalanches were triggered over the last couple days, including one where a rider took a small ride in Corner Pocket in the Baker backcountry on Tuesday. There is a lot of uncertainty regarding the existence of weak, persistent layers at the bottom of the new snow, one to two feet down. This layer of concern is most likely to be found on upper elevation slopes on the northerly half of the compass.

    A lull in precipitation will help to stabilize wind slabs that failed within the new snow layer, but it will not do much to stabilize weak layers beneath the new snow. So far, the most notable avalanches remain limited to pockets of this potential weak layer. It may not exist as large swaths, but we aren’t sure how widespread the layer is. Take this into account if you’re keen to jump out onto large, steep and exposed northerly slopes. In all areas you travel, continue to feel for changes in snow hardness. Plunge your poles into the snow to check snow depths regularly if you use them. Search for drifting on convex rolls, near rocky outcroppings, and in gullies. Pay attention to cracking and whumphs, clear signs that a steep slope could avalanche. If you find any of these characteristics, stick to lower angle terrain and avoid nearby steep slopes.

    (1/31/2022) A large remotely triggered avalanche on the Shuksan Arm in the Baker backcountry. Note where the riders are standing, on the ridgeline, near where the avalanche was triggered from. They noticed whumphing before the avalanche occurred.  Photo: Mt Baker Ski Patrol

Avalanche Discussion

Around a foot of new snow fell since Saturday night around the West North zone, mostly limited to near and above treeline areas. Observations near treeline found wet snow made for a good bond to the wide variety of old snow surfaces. Avalanches at this elevation were shallow and released within new snow layers. It is a different story moving into alpine terrain as colder snow may have preserved weak snow surfaces and provided the setup for surprising avalanches like the one that occurred on Shuksan Arm on Monday. 

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