Boletín de aludes

Central Sierra Nevada

Sierra Avalanche Center
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Peligro de aludes

Alta montaña
1 · Débil
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Triggering an avalanche has become unlikely on a regional scale. Unlikely does not mean impossible. Unstable snow may still exist on an isolated terrain feature especially in areas with a shallow snowpack where old weak snow sits closer to the surface. Keep looking for any signs of lingering instability and be willing to step back into safer terrain to minimize the chances of an unpleasant surprise. The avalanche danger has dropped to LOW at all elevations. 

Problemas de aludes

  • Persistent Slabs

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

    On a regional scale, persistent slab avalanches have become unlikely. Most data targeting the persistent weak layer (Dec 11 facets) indicates it has adjusted to the current load. No known avalanche activity has been reported on the old weak snow since before the last storm on Jan 6. Further investigation of 2 large avalanches reported earlier this week found that one of them was a case of mistaken identity and was not actually an avalanche. The other likely was not what it seemed either. The last reported whumpfing on this layer came from Pickett Peak on Jan 6. While some snowpit tests continue to yield unstable test results in some places, the majority of them do not indicate instability. The unstable results continue to come from areas with a shallow snowpack like places near Carson Pass and Ebbetts Pass and lower elevation areas in other parts of the forecast region. Uncertainty about this problem still exists and while unlikely, a persistent slab may not be impossible on an isolated terrain feature.

    Gather information about whether or not old weak snow exists below the surface by probing and digging into the snow and looking for any signs of instability while traveling. Finding unstable snowpit test results or other signs of instability including whumpfing or cracking could indicate you are in one of the isolated areas where an unlikely but not impossible persistent slab might be hiding. If you find yourself in one of those areas, step back and use terrain to avoid the problem by traveling on slopes less steep than 30 degrees not connected to steeper slopes. 

Avalanche Discussion

Recent Observations:

* Yesterday, observations from Chickadee Ridge (Mt. Rose backcountry), Martis Peak (Brockway Summit), and Silver Peak (between Tahoe City and Truckee) did not find signs of instability associated with the Dec 11 facet layer even in areas with a more shallow snowpack. 

* Farther south in the Meiss Ridge area (Carson Pass) snowpit tests showed unstable results on the Dec 11 facet layer, but no other signs of instability. 

* Blowing snow and small drifts of snow with minor cracking were reported on Chickadee Ridge. Observers reported blowing snow without significant drifting and no signs of wind slab instability on Martis Peak, Meiss Ridge, and on the lower elevations of Silver Peak. 

* Observers continued to report variable snow surface conditions yesterday with some soft snow on sheltered upper elevation slopes. In more exposed areas wind-scoured, wind-packed, and rain crusted surfaces existed.  At lower elevations, a widespread sometimes breakable sometimes supportable rain crust existed.

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