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 on NW-N-NE-E-SE 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

    While wind slabs have become more difficult to trigger, some human triggered wind slab avalanches will remain possible today. Unsupported snow slopes above cliffs, wind loaded steep couliors, and other complex or extreme terrain will represent the best places to find fragile wind slabs, but they could also still linger on other wind loaded NW-N-NE-E slopes in near and above treeline terrain. Due to the winds shifting between south and southwest some wind slabs could also still lurk on isolated 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

    As the new snow continues to consolidate, storm slabs should become more difficult to trigger. That being said, some of these storm slabs may be resting on an old snow surface that shows some evidence of becoming a persistent weak layer in a few areas. Today human triggered storm slab avalanches that fail on a lingering weaknesses in the storm snow or on the interface between the storm snow and the old snow below it still remain possible. Steep NW-N-NE facing slopes in near and below treeline terrain represent the most likely places to find lingering storm slabs and the most likely aspects where the old snow surface could start behaving more like a persistent weak layer. Some storm slabs may also remain possible on steep E facing aspects as well. Storm slabs on other aspects have become unlikely but not impossible. 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 where the storm slabs rest on old snow surfaces that have started behaving like persistent weak layers.

Avalanche Discussion

Yesterday small human triggered storm slab avalanches occurred on Red Lake Peak, Andesite Ridge, and on Talking Mountain. On Red Lake Peak and Andesite Ridge these slides measured about 12 inches in depth while smaller slides less than 5 inches in depth occurred on Talking Mt. All of these avalanches occurred on steep N-NE facing aspects. Reports indicate that the Andesite Ridge slide and possibly the Red Lake Peak slide occurred due to a weakness at the old snow surface just below the recent snow while the ones on Talking Mt. occurred within the recent snow. In addition to these storm slabs skier triggered loose dry sluffs/point releases also occurred on Talking Mt., Red Lake Peak, and Tamarack Peak. On more exposed wind loaded test slopes some skier triggered cracking occurred on Talking Mt. and on Tamarack Peak. Snowpit data from Tamarack Peak and Red Lake Peak showed that the snowpack has started to bond in some areas while other data (a.k.a. the avalanches mentioned above) clearly indicated that poor bonding exists in other areas. 

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