Boletín de aludes

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Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

You can trigger loose dry avalanches in the recent snow on a range of steep slopes. While larger slab avalanches are unlikely, it's worth considering the consequences. If you experience whumpfing collapses, cracks shooting through the snow, stick to slopes under 35 degrees to manage this less likely, but more dangerous situation.

Problemas de aludes

  • Loose Dry

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

    The recent snow is dry, cold, and mostly cohesionless. The frigid temperatures and very light new snow are maintaining these "cold smoke" conditions. The most likely of today's avalanches will be loose and more predictable than slabs. You may see natural avalanches on steep sunny slopes. Manage your terrain appropriately by stopping in safe locations, and don't trigger sluff on top of your backcountry partners. 

    Under the new snow there's a widespread layer of weak facets. If you find more cohesive storm snow (perhaps west of the Cascade Crest), you could trigger slab avalanches 1-2 feet deep in the recent snow. They could even be surprising and break widely across terrain. Use quick hand pits and test slopes to see and feel how the new snow reacts.

    (1/31/2025)

    Skiers easily triggered dry loose avalanches like in this photos over the weekend. 

    Photo: Chris Bartram

Avalanche Discussion

A strong storm brought significant precipitation on the 31st-2nd with light accumulation continuing since then. The new snow is very light and cold. The old interface, dubbed "January Drought Layer," is now 1-2 feet below the surface. West of the Cascade Crest, you may find even more recent snow. Winds transported snow on the 1st, but have been light since then.

While unlikely, it's worth considering the potential for persistent slab avalanches, especially where west and southwesterly winds drifted snow around Feb 1st. You'll have to probe or dig to feel for these stiffer slabs as they're now under more recent soft snow. Throughout this zone, there are two significant persistent weak layers, the JDL (or Jan 31st) and a deeper layer of facets buried in mid-December (see below). There have been a number of these dangerous avalanches triggered on the JDL in the neighboring West North zone, and even more so in the more distant zones to the south. Like some other zones east of the Cascade Crest, much of the recent snow in the East North zone lacks cohesion or "slab" characteristics. 

 On Sunday, an NWAC observers investigated an avalanche near the Snagtooth Ridge that was triggered in an old weak layer up to 3ft deep. (See video) The avalanche was triggered at 6,600ft on a northeast aspect from a shallow spot in very steep, rocky terrain. The weak layer was into the lower half of the snowpack and was 1-2mm faceted grains. It's believed that these facets were buried on December 17th. On Monday, an NWAC Forecaster found a similar snowpack structure on northerly aspects adjacent to Silver Star Creek. There, the weak layer wasn't problematic for human triggering. 

The persistent slab avalanche on Snagtooth Ridge that propagated into older, deeper snow layers highlights our complex and variable snowpack.  This could be an isolated incident, but it's probably best to keep it in mind when choosing terrain. Consider avoiding shallow, weak areas in the snowpack, typically found in or near steep, rocky terrain. 

You can help us gather more data by submitting an observation HERE or via the Avy App. 

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