Boletín de aludes

Central Sierra Nevada

Sierra Avalanche Center
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Peligro de aludes

Alta montaña
4 · Fuerte
Límite del bosque
4 · Fuerte
Bajo el límite
4 · Fuerte
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Desactualizado: este boletín caducó 10 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

HIGH avalanche danger continues for all elevations and aspects due to a combination of wind slab, storm slab, and deep slab avalanche problems. Travel in avalanche terrain, on or below slopes 30 degrees and steeper is not recommended. Avalanches could run into areas of mature forest. A backcountry avalanche warning remains in effect through 5 pm today.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Very Likely
    Tamaño
    3

    Natural wind slab avalanche activity occurred yesterday. Ongoing gale force SW winds and additional snowfall on top of the numerous feet of new snow already received will continue to create very large wind slabs in near treeline and above treeline terrain mainly on NW-N-NE-E-SE-S aspects. Wind slabs may exist in more isolated areas on SW-W aspects and in below treeline areas as well.

    Travel on or below slopes steeper than 30 degrees is not recommended today. Very large cornices exist along ridgelines, presenting an additional hazard.

  • Loose Dry

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

    Human triggered storm slab avalanches were reported yesterday from below treeline areas. Multiple feet of new snow accumulation in wind protected areas combined with fluctuating snow levels and air temperatures has created storm slabs on all aspects in near and below treeline terrain. An upside down storm snow structure exists in many areas with numerous density changes within the storm snow.

    Travel on or below slopes 30 degrees and steeper is not recommended. Trees will need to be too tight to move through on skis or a snowmobile to protect from direct human triggering of this avalanche problem. Keep in mind that avalanches from above can move through mature forest.

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    3

    Several possibilities exist for deep slab avalanches characterized by failure more than 3 feet deep in the snowpack to occur today. Drifting snow associated with wind slabs has become deep enough to qualify as deep slabs. Numerous density changes exist within the storm snow. Failure much deeper in the snowpack down to the depth of the Dec 15 rain crust remains possible, especially above 9,000'. Deep slabs could occur on any aspect at any elevation.

    Human involvement in any deep slab avalanches will be difficult to survive given the expected very large to historic avalanche size. Travel on or below slopes 30 degrees and steeper is not recommended. Avoid historic avalanche run out zones characterized by small to medium sized trees with steeper slopes above.

Avalanche Discussion

Numerous avalanches ranging from small to very large were reported yesterday around the forecast area. A skier triggered storm slab avalanche occurred on Powderhouse Peak (Luther Pass area) on a N aspect at around 9,100'. The avalanche was reported to have a 1 foot crown, propagate over 300 feet wide, ran 1,100 vertical feet through mature forest, and overran the skin track below. No one was caught in the avalanche. Additional sensitive storm slabs and avalanche activity was reported below treeline yesterday afternoon near Coyote Rock outside the community of Meyers, CA. Sensitive wind slabs with easy skier triggering were observed on test slopes in Negro Canyon (Donner Summit area). Signs of larger natural wind slab avalanche activity existed in obvious avalanche paths in the area.

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