Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

Wed
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The upper snowpack continues to strengthen, however you can still trigger an avalanche on steep rollovers and in wind-loaded terrain. Recently formed cornices can help you avoid recently wind-loaded terrain on the slopes below. Snow immersion and suffocation remains a risk, so maintain visual contact with a partner.

Problemas de aludes

  • Wind Slabs

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

    From Thursday through Sunday, the snowpack around Mt. Baker increased from 50-80" and has since consolidated to 72". Southerly winds redistributed 3-4 ft of storm snow, forming cornices and wind slabs. While the likelihood of triggering a slab continues to decrease, the size remains large. Focus on your terrain selection, steering around higher consequence areas and steep slopes that roll away from you, especially as you make your way towards ridgelines and above treeline elevations, where wind slabs can take up to 5 days to settle out. Look for evidence of strong over weak layering. Search for ripples or wind-sculpted snow and nearby cornices as clues that you could be entering a wind deposit. Avoid steep slopes where you encounter these conditions as well.

    In the event that you find shooting cracks or experience a whumphing collapse, these slabs could be sitting on a weaker interface. Recalibrate and select more conservative terrain.

     

     

    (12/11/2022)

    A wind slab triggered in the neighboring East North zone serves as a reminder to avoid slopes under growing cornices.

    Photo: Erin Andrade

Avalanche Discussion

Large slab avalanches up to size 2.5 released naturally on a variety of aspects around Table Mountain (see photos in the gallery). These slides ran on the 11/25 facet crust combo and serve as a reminder that an isolated large avalanche could still be triggered days after a storm on a weaker interface.

Significantly colder temperatures helped dry out and stabilize the snowpack by Monday morning, yielding much-improved riding conditions. Slope testers were out on Monday with no reported reactivity. With little change in the weather forecast for Tuesday, it's the amount of recent snow that keeps us at moderate near and above treeline. Small dry loose or sluff avalanches were minimal on Monday, but still may be of concern in high-consequence terrain. Observers also reported rollerballs on steep south-facing slopes. With another sunny day, expect a repeat scenario on steep, sun-exposed slopes on Tuesday.

NWAC and the Mt. Baker Pro Patrol regret to pass along news of a fatality involving Snow Immersion and Suffocation (SIS). Unwatched while riding in an inbounds, extreme terrain, he ended up positioned in deep snow such that he was unable to self-extricate. We offer condolences to everyone directly and indirectly impacted.

SIS remains a concern on Tuesday in deep, slowly consolidating snow, particularly near trees. Check out the film below for more information that could be life-saving. 

Before the storm on Friday, an observer reported triggering a small avalanche in an open meadow below treeline. You can read the observation HERE. The observer found feathery crystals, which were likely surface hoar, below the 40cm thick slab. Surface hoar was also found in a pit dug by a Pro 1 avalanche class in the Baker backcountry at around 5000ft, buried almost 3 feet down on a NE aspect on Sunday. They got a propagating extended column test (ECTP28) result on the layer, indicating that it might take a lot of force for the layer to be affected, but if it fails, it could propagate, resulting in an avalanche. This was found in one pit amidst several they dug. We don't know much about this layer right now, and most information we've gotten from it has been inconsistent. However, several zones are finding this layer, and a few avalanches have been reported as failing on it so far. 

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