Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Unstable areas where wind drifted snow has deposited as slabs (wind slabs) remain possible today in a variety of locations above treeline and near treeline. Some wet loose avalanches will become possible on sun exposed slopes at all elevations as daytime warming melts the snow surface. MODERATE avalanche danger exists today for all elevations.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Ridgetop winds shifted last night from SW to NE and there was plenty of recent storm snow on the ground available for drifting. A patchy mix of wind scoured areas and drift deposited wind slabs are expected on all aspects in above treeline and near treeline terrain. Avalanche size up to D2 remains possible. Several wind slab avalanches were skier/snowboarder/snowmobiler triggered yesterday so signs of recent avalanches may be visible today.

    Use clues such as recent avalanches, blowing snow, cornice formations, wind pillows, and textured snow surfaces to determine where unstable wind slabs may exist. Move around these areas with caution. Avoiding wind loaded above treeline and near treeline areas in favor of more sheltered below treeline terrain will help limit exposure to the wind slab avalanche problem and may provide more consistent snow conditions.

    (03/20/2021) Skier triggered avalanche on Red Lake Peak, CA. Drifting snow visible along the ridgetop.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    As air temperatures climb above freezing today and sunny skies allow for strong incoming solar radiation, a wet loose avalanche problem will become possible. Avalanche size is expected at D1 to D2. The majority of wet loose avalanche problems will form on E-SE-S-SW-W aspects and to a lesser extent on sun exposed NW-N-NE aspects.

    As the snow surface starts to melt and become wet, recent new snow will show roller balls and pinwheels as indicators of developing instability. This avalanche problem will form quickest in wind protected areas near exposed rocks, eventually spreading to other areas as winds decrease and air temperatures continue to warm. Exercise caution on or below steep slopes where surface wet snow, roller balls, and/or pinwheels are present.

Avalanche Discussion

* An unfortunate and tragic cornice fall accident occurred yesterday above Frog Lake (Donner Summit area). Our condolences go out to the family and friends of the deceased. What details we know about this accident are listed here.

* Large fragile cornices still exist along ridgelines in some areas. These cornices may further weaken today in response to warming.

* Skier/snowboarder/snowmobiler/cornice fall triggered wind slab avalanches occurred yesterday in above treeline and near treeline terrain on N to NE aspectsAvalanches were mostly size D2.

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