Boletín de aludes

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
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

Our most recent snow came in cold and light, followed by strong wind from abnormal directions. At upper elevations hard wind slabs developed, including on aspects that don’t typically see significant wind loading. The wind slabs vary in thickness and strength and are difficult to predict. The wind slab problem is easy to avoid by spending time on sheltered mid-elevation slopes, where you will find the best riding conditions anyways.

Problemas de aludes

  • Wind Slabs

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

    While touring yesterday we found very stiff wind slabs that supported our weight right next to soft slabs that broke easily. Abnormal winds from the north and east transported snow to south and west aspects where we do not typically see wind slabs form.

    Wind slabs are difficult to predict because it is possible to trigger a fracture in a thin section of wind slab that propagates into thicker more dangerous portions of the slab. This can trigger a hard slab avalanche around and above you. The best way to mitigate this hazard is to avoid steep wind-loaded terrain, including ridges, saddles, and cross-loaded terrain features like gullies. Sheltered trees will be where you find the best powder stashes left from the most recent storm.

  • Persistent Slabs

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

    The January crust had broken down significantly where I investigated yesterday. What remained was a pronounced weak faceted layer 20 inches below the surface. This layer did not propagate or show signs of reactivity in stability tests, but it’s still there. The danger of layers like this is they can “sleep” for months until loading, the right conditions, and a triggering event “wake” them. While unlikely at the present time the results can be catastrophic.

Avalanche Discussion

Yesterday, we toured out of Lookout Resort to Eagle Peak and the ridge leading toward Stevens Peak. The temps were not as cold as previous days and we enjoyed blue bird sky.

We found a cold upper snowpack. This is notable for two reasons: First, this may slow the bonding and settling of wind slabs a little. Second, it will have preserved soft powder in shaded and wind sheltered terrain. What that mean? Good tree skiing and riding at mid-elevations.

The incremental warming with light winds over the next few days bode well for increasing stability throughout the area. It’s a great time to get out and enjoy the mountains.

IPAC still has spots open Wilderness First Aid for Winter Backcountry Users and Avalanche Level 2 classes. These are great opportunities to improve your skills with knowledgeable local instructors. Check them out here!

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