Boletín de aludes

Central Sierra Nevada

Sierra Avalanche Center
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Peligro de aludes

Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 7 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

LOW danger will increase to MODERATE avalanche danger at all elevations today as the day warms up. Loose wet avalanches will represent today's main avalanche problem, but some isolated and unlikely wind slab problems may also still exist in a few areas. 

Problemas de aludes

  • Loose Wet

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

    Strong sunshine and warm weather should quickly melt through last night's refreeze. Loose wet avalanches large enough to cause serious problems for backcountry travelers could occur today, especially on long, steep, sun-exposed slopes. E-SE-S-SW-W aspects will be most susceptible since they will experience the full force of the spring sunshine. Some wet snow may form on sun-exposed northerly aspects as well.

    Wet, heavy surface snow and/or pinwheels or roller balls formed as the refreeze melts can foreshadow larger loose wet avalanche activity. Once the melt starts, it is time to seek out colder more shaded aspects. These colder aspects are the areas where softer snow may still exist and should hold less hazardous avalanche conditions. 

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Unlikely
    Tamaño
    1

    Settlement and consolidation in the new snow should make triggering a wind slab avalanche unlikely in the majority of areas today. Unlikely does not mean impossible. An isolated wind slab failure cannot be ruled out in some complex or extreme terrain (like couloirs, cliffy areas, unsupported slopes, and steep convex rollovers) or in response to a very large trigger (like a large cornice collapse).

    Variable, challenging, wind affected snow conditions will exist in areas where difficult to trigger wind slabs may still linger. Avoiding these less fun snow conditions in favor of the softer snow that should still remain in more sheltered terrain could provide more enjoyable recreation and help avoid potentially unpleasant wind slab surprises.

Avalanche Discussion

* Yesterday two human-triggered wind slabs were reported: one snowmobile triggered near Indian Valley and one triggered by a ski cut piece of cornice on Mt. Judah. Both of these had crown depths of ~ 1 ft. Both occurred on steep-exposed wind-loaded slopes in near and above treeline terrain.

* Observations in exposed above treeline areas on Mt. Rose and on Trimmer Peak also found signs of lingering wind slabs. On Trimmer, a small test slope failed in response to a ski cut. On Rose, some cracking occurred in response to a ski kick on a previously undercut slope. 

* Observations from less exposed areas around Blue Lakes, Indian Valley, Mt. Rose, and Trimmer Peak did not find signs of lingering instability despite numerous ski and snowmobile cuts on test slopes.  Warm wet surface snow and some small inconsequential warming instabilities did start to form by the afternoon in all of these areas on sun-exposed slopes.

 

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