Boletín de aludes

West Slopes Central

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

A sharp uptick in avalanche danger will occur on Monday as a storm deposits snow Sunday night and Monday. It is likely that avalanches will occur in storm snow layers, although they will probably be more reactive in wind-loaded spots. Sticking to lower-angle terrain during this storm is the best way for you to avoid triggering and getting caught in an avalanche on Monday. 

Problemas de aludes

  • Storm Slabs

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

    A few factors are going into the avalanche problem on Monday, but let's keep it simple: A storm will deposit around 6 inches at upper elevations overnight and then more than that amount during the day. Human-triggered avalanches are likely. Stick to slopes less than 35 degrees to avoid triggering avalanches and give the snowpack time to adjust. 

    Strong winds overnight may mean that wind-drifted areas are where you'll find large enough snow deposits and more reactive layers to trigger an avalanche early in the morning. Wind will decrease during the day, and wind slabs could be disguised under a less conspicuous, smooth layer of snow. As the snow builds, you can expect to find avalanches on non wind-affected steep slopes. Freezing levels will drop during the storm, so for the first time in a while we can expect to see snow at lower elevations and the Considerable avalanche danger may drop below treeline. Expect to find storm slabs at lower elevations, and as you work your way above treeline more slopes will have a wind influence, with drifted areas likely forming into larger and more reactive slabs. Don't discount non wind-affected slopes with deposits greater than 6 inches. 

    Snow forecast amounts vary, so be sure to evaluate areas where you're traveling to determine the extent of slab developments, and adjust the avalanche forecast based on your findings. Storm snow deposits will be shallow enough that you can use hand pits and test slopes to check the bond with the old snow layer. When in doubt, stick to slopes less than 35 degrees. 

    Storm slabs like this may easily be triggered on Monday.

    Photo: Andrew Kiefer

Avalanche Discussion

Since the storm ending on 2/7, avalanches have been triggered on a slightly weak layer above a crust in both the West North and Stevens Pass zones, failing around 2 feet deep, beneath last week's storm snow. I've dug several pits in both of those zones in the last week, without finding alarming layers of concern in those pits, yet we still infrequently have avalanches failing here. One was reported in the West North zone, remotely triggered by a snowmobiler late Saturday, and another also occurred that day at Stevens Pass, which involved a partial burial. This layer is spooky, and we don't expect it to go away overnight. Clearly, it's difficult to find in pits so digging isn't a solution. This also isn't an avalanche we want to get caught in. They've been found to occur near and above treeline on wind-loaded slopes. For now, if you choose to travel into steep near and above treeline areas be aware that there is a very small chance you could trigger an avalanche on this layer. 

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