Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
1 · Debole
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 13 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Near treeline and below treeline avalanche danger remains MODERATE on NW-N-NE aspects on slopes steeper than 32 degrees due to lingering persistent slab instability.

Human triggered avalanches remain possible. 

Problemi valanghivi

  • Deep Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2

    Persistent slab instability remains ongoing near treeline and below treeline on NW-N-NE aspects. The faceted Dec 7 persistent weak layer is slowly gaining strength, but not enough to make much difference in terms of reducing avalanche danger. Between the lingering persistent slabs and the shallow snow cover over rocks, logs, and other objects, significant hazard exists in the backcountry.

Avalanche Discussion

Observations made yesterday on Red Lake Peak (Carson Pass area) matched well with other recent observations from around the forecast area. Persistent slab instability lingers near treeline and below treeline on NW-N-NE aspects. The Dec 7 facet layer is buried under a fairly well consolidated slab and remains reactive in snowpit tests. Once this weak layer collapses, it has the necessary characteristics to allow a fracture to propagate through the snowpack.

Spacial variability is increasing around the forecast area in regards to stability improvements of the Dec 7 faceted weak layer. The amount of force required to trigger weak layer collapse and the ability for the weak layer to propagate are becoming more variable from one location to another. In some spots, strength increases in the Dec 7 persistent weak layer are highly evident while in other areas the strength gains have been much more modest. Either way, the data still indicates that human triggered avalanches are possible in many locations around the forecast area.

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