Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

Mon
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
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

Avalanche danger will decrease as the storm tapers, but plentiful new snow requires investigation before committing to bigger terrain. When in doubt steer towards more planar, supported, and lower-angle terrain. Pay attention to sunny slopes if the clouds thin out in the afternoon. 

Problemas de aludes

  • Storm Slabs

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

    The risk of triggering an avalanche is usually higher in wind-loaded terrain, but there is enough new snow to look for instability on all slopes, wind-loaded or not.  Slabs can be more reactive when they get their first hit of sun and warming. Expect deep new snow to sluff easily where less of a slab has formed.

    Pay attention to signs of instability like whumping, shooting cracks, or recent natural or human-triggered avalanches. Track the depth of new snow as you gain elevation and change aspects by measuring how much new snow sits over the rain crust. Use wind-drifted features, test slopes, and other simple tests to evaluate the bond of new and wind-drifted snow layers.  

    If avalanche conditions are looking favorable wherever you end up in West North, ease into more aggressive terrain instead of diving headfirst. Pick slopes with no terrain traps in the runout below to reduce risk if you do trigger an avalanche.

    (1/1/2023)

    Slab avalanche in a steeper terrain feature below a cliff.

    Photo: Jeff Hambleton

Avalanche Discussion

Look for the sun to make an appearance as we get a lull between storms. Warming should be limited by clouds, cooler temperatures, and the low sun angles of mid-December. Either way, keep an eye on slopes picking up sun and look for signs of instability like rollerballs and snow shedding from trees and cliffs. You could start seeing small loose snow avalanches if warming is greater than expected.

It was a bit of a wild day out there on Saturday with wind gusts approaching 60mph and almost two feet of new snow in some areas. Observations were mixed. The Mount Baker Ski Area reported numerous large avalanches with control work on Saturday morning and also a handful of human-triggered avalanches in nearby backcountry terrain. Some backcountry observers found thick wind slabs of moist new snow became unreactive midday. Cracking and other signs of instability also tapered off.  But another team triggered an avalanche from low on a slope in Upper Bagely with one person caught and partially buried.  No natural avalanches were observed but visibility was too poor to say for sure.

The amount and pattern of redistribution from strong to extreme winds were fascinating, with drifts 3' or deeper immediately next to areas where the old rain crust was exposed at the surface. At this point, it's impossible to say if weak facets at and just below the old snow surface are contributing to observed avalanche activity. Snow profiles on Saturday were inconclusive. With the variation and depth of wind deposition, you can't really tell if an avalanche released in older, weaker layers based on crown depth alone.  The extent of natural avalanche activity and more observations will hopefully answer this question on Sunday.

 

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