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 10 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

MODERATE avalanche danger exists on slopes steeper than 35 degrees on all aspects due to the possibility of loose wet avalanches below 8500 ft. and wind slabs on near and above treeline W-NW-N-NE-E-SE aspects above 8500 ft. Some human triggered avalanches will be possible today. Evaluate snow and terrain carefully, and identify areas where avalanche problems might exist.

Problemi valanghivi

  • Loose Wet

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

    Loose wet snow instabilities like roller balls, pinwheels, and some point releases will be possible again today on slopes steeper than 35 degrees on all aspects below 8500 ft due continued rain on snow and a lack of an overnight refreeze.  While many of these loose wet snow instabilities should remain relatively small and easy to avoid, some of the larger ones could entrain significant amounts of snow and cause problems for backcountry travelers. Steep slopes that receive rain below 8000 ft. represent the best places to find loose wet snow issues today, but these wet snow issues could also creep up to higher elevations where very wet snow falls on the surface.  

    Avoid slopes with deep wet snow on them that are steeper than 35 degrees or have terrain above that is 35 degrees or steeper. Active roller balls and pinwheels indicate that loose wet snow avalanches can occur. 

  • Wind Slabs

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

    New snowfall today and this evening, gale force south and southwest winds, and some snow still available for transport on the windward aspects mean that new wind slabs could start forming on the snow surface of leeward slopes today. Due to the small amounts of new snow expected today and the fact that much of the snow available for transport has become very wet and heavy and hard to move, most wind slabs that do form today should remain relatively small and not extend very far away from ridgelines. Some larger more problematic wind slabs could form on leeward near and above treeline slopes above 8500 ft. where more snow falls today and where colder more easily transported snow from previous storms still exists on some of the windward aspects. Due to the more southerly nature of the winds wind slabs may form in unusual areas. Wind loaded NW-N-NE-E aspects and cross loaded W and SE aspects above 8500 ft. will represent the best places to find human triggerable wind slabs today. 

    Identify and avoid steep wind loaded slopes.  Look for areas of blowing snow, cornice formation, wind scouring, and wind pillows to help determine where wind slabs exist.

Avalanche Discussion

Yesterday observations on Carson Pass near Frog Lake and on Barker Pass both showed wet snow on all aspects up to at least 8500 ft. Human triggered loose wet snow instabilities like large pinwheels and roller balls occurred on steep slopes in both areas. These wet snow instabilities also existed on most aspects including the northerly ones. Rain runnels had formed on the snow surface below 7600 ft. in the Barker Pass area. In the Frog Lake area strong winds transported some snow onto the N-NE-E aspects, but observers did not report any significant wind slabs. 

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