Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 11 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Human triggered avalanches remain possible today due to lingering wind slabs and storm slabs. MODERATE avalanche danger exists on all elevations and aspects on slopes 35 degrees and steeper. Evaluate snow and terrain carefully before committing to any slopes. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    3

    New snow and shifting winds since Jan. 5th have created wind slabs on leeward aspects. Additional wind and snow last night caused these wind slabs to continue to grow in size and extent. These wind slabs have started to bond to themselves and the snow below them, but human triggered wind slab avalanches will remain possible today. The most sensitive wind slabs will exist on wind loaded slopes in near and above treeline terrain. Due to the winds shifting between south and southwest these wind slabs could exist on wind loaded NW-N-NE-E aspects as well as cross loaded W and SE aspects. Avalanches resulting from the failure of these wind slabs would easily involve enough snow to bury a person and could be even larger in the most heavily wind loaded areas.  

  • Loose Dry

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

    Like the wind slabs mentioned above storm slabs have also become more difficult to trigger since they have started bonding to the snow below them. Still the possiblity remains for a human triggered storm slab avalanche that fails on a lingering weakness in the storm snow or on the interface between the storm snow and the old snow below it. Steep northerly facing slopes in near and below treeline terrain represent the most likely places to find lingering storm slabs, but they could still exist on any aspect in near and below treeline terrain. Storm slabs that have the ability to propagate far distances or be remotely triggered have become more unlikely, but that potential may still exist in a few isolated areas. 

Avalanche Discussion

Yesterday, observations on Andesite Peak showed that the storm slabs from Jan. 5th had started to bond to the snowpack below them. Snowpit tests and ski cuts on test slopes in near and below treeline terrain did not produce signs of instabilities on the interface between the recent snow and the old snow. On Rubicon Peak some snowpit and hand pit tests showed signs of instability concerning the storm slabs in near and below treeline terrain and other tests did not. Yesterday morning in more exposed near and above treeline terrain on Andesite Peak and Rubicon Peak, some shooting cracks did occur on wind loaded test slopes. On Andesite cornice pieces dropped onto these wind slabs triggered the cracking. On Rubicon ski kicks/cuts triggered it. The wind slabs measured 2-3 ft. in depth. A few hours later during the afternoon on Rubicon, ski cuts on similar wind loaded test slopes failed to trigger additional shooting cracks.

Regioni coperte