Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

Sat
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

Warm temperatures and sunshine will maintain concern for wet snow avalanches. Monitor snow surfaces as they thaw throughout the day. Continue to evaluate conditions carefully before venturing into steep, north-facing alpine terrain where a weak snowpack structure may linger.

Problemas de aludes

  • Loose Wet

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

    Sticky snow surfaces were observed up to 5400ft on all aspects the past couple of days with rollerballs and a few wet loose avalanches. Cloudy, warm, muggy weather with a "greenhousing" effect already caused surfaces to become wet. But, continued warm temperatures with a full day of sunshine Friday could allow for additional wet avalanche activity. Pay attention to how snow surfaces thaw throughout the day and keep your return routes in mind. Slopes you crossed safely earlier in the day may be wet and unstable by afternoon. Watch for fresh rollerballs and pinwheels as signs that loose wet avalanches could follow on similar slopes. If you find wet, slushy snow, move to shaded or lower angle terrain to reduce your risk of triggering an avalanche.

    (2/10/2022)

    Small natural wet loose avalanches on a northerly aspect near 4500ft in Bagley Basin.

    Photo: Irene Henninger

  • Persistent Slabs

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

    We continue to receive reports of large avalanches on the late January crust-facet layer. The most recent avalanche occurred Tuesday high on Shuksan Arm. The crown was around 2ft deep and 600ft wide, and debris ran far downslope with observers reporting a “big pile” on the valley floor. The following is what we know about avalanches on this persistent weak layer:

    • The snowpack structure is inherently weak.
    • The layer is still reactive above 5000ft on aspects that did not receive strong sun in late January.
    • Reported natural and human-triggered avalanches occurred at the same aspects and elevations.
    • They mostly occurred where there are 2 or more feet of recent snow over the crust-facet layering.
    • Snowpack tests produce inconsistent results at the crust-facet layering, sometimes even in the same snowpit.
    • Many steep slopes - some very near avalanches that released in the same layers - have been ridden and skied with no results.

    The conclusion so far is that there are very few places where you could trigger one of these avalanches. At the same time, it would not be a surprise if another one occurred. Very warm temperatures over the next few days adds to the uncertainty and could even increase the likelihood of these avalanches. 

    (2/1/2022)

    This persistent slab avalanche occurred not long after the weak layer was buried. It was remotely triggered, in an isolated location.

    Photo: Mike Trowbridge

Avalanche Discussion

Large cornices could sag and fall as very warm temperatures continue. A falling cornice on the right slope could even trigger a persistent slab avalanche. Pay attention to slopes above you and give cornices a wide berth, especially during the heat of the day. 

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