Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Triggering a wet avalanche is becoming less likely as temperatures cool, but still steer around steep slopes that hold wet, mushy snow underfoot or sled. On slopes with cold, dry snow, triggering a widely propagating slab isn't off the table yet. 

Problemas de aludes

  • Wet Slabs

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

    Wet snow is complex and can be unpredictable. While cooling temperatures are helping the snowpack gain strength, it still remains possible to trigger wet avalanches in places you find wet, unsupportable snow. A thin surface crust doesnt always eliminate the chances of triggering one of these beasts. Slopes can remain unstable while water percolates down through the snowpack. Wet avalanches may run naturally, or you could trigger a widely propagating wet slab on deeply buried weak layers from Early February. 

    You can reduce your exposure to these wet avalanches by traveling on slopes that are supportable and firm. Be suspect of slopes greater than 30 degrees that feel wet and sloppy. Stay off of and out from large or consequential avalanche paths where you're sinking in past your ankles in a mushy snowpack. 

    (1/29/2024)

    An example of wet slab from earlier this season. 

     

  • Persistent Slabs

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

    Areas with wet snow have been the primary focus, but triggering a large unsurvivable avalanche where the snow has stayed dry isn't off the table yet. These avalanches would fail 2-4 ft deep on layers of faceted snow adjacent to the Early February Crust (EFC). 

    The most likely place you could trigger one of these would be shaded aspects at upper elevations. Be suspicious of steep, rocky, wind affected terrain. You can reduce your risk by avoiding this type of terrain. 

    (3/16/2024)

    A very large slab avalanche that likely occurred 3/15.Chiwaukum Range, 6,600ft, NW

    Photo: Stevens Pass Patrol

Avalanche Discussion

Gradual cooling is slowly helping reduce the chance of triggering wet avalanches. However, keep in mind that a weak snowpack structure did exist prior to this warm-up. On 3/20 an observer on Dirtyface Mountain reported a large whumph on an east aspect at 5700 ft. In this location, the surface snow was moist, but it serves as a reminder that weak layers are still present despite the recent warm-up.  NWAC Forecaster, Katie Warren traveled  near Mission Ridge and found a more significant overnight refreeze that led to a more supportable crust during the morning hours. She also reported the snow over the Early February Crust (buried 45cm deep) is still notably weaker than the overlaying slab, but the faceted grains were moist and rounded. You can check out her observation here. 

A close call on the 16th, where snowmobilers triggered a very large avalanche in Ahtanum (East South) that failed on deeply buried weak layers, is an indication of the potential for these types of avalanches as we continue to warm the snowpack. Other notable wet slab avalanches and wet loose avalanches occurred throughout the weekend in the Teanaway. Avalanche debris came close to covering the North Fork Teanaway road at the valley bottom and, in one location, was estimated to be 15-20ft deep below a confined gully feature.

Your avalanche, snowpack, or weather observations are extremely valuable to the avalanche community. Help create a more accurate avalanche forecast by submitting your observations here. 

 

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