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
Non aggiornato — questo bollettino è scaduto 11 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

This morning LOW avalanche danger exists on all elevations and aspects. MODERATE avalanche danger will form on E-SE-S-SW-W aspects steeper than 35 degrees as human triggered loose wet avalanches become possible due to daytime warming. Small roller balls, pinwheels, and loose wet point releases will represent the majority of the loose wet instabilities today but some of them could be large enough to pose a danger to backcountry travelers. 

Problemi valanghivi

  • Loose Wet

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

    Even though overnight lows remained above freezing in many places, the snowpack should have radiated enough heat out into the clear night sky for a weak overnight refreeze. Today's plentiful sunshine and warm daytime temperatures will quickly melt through this weak refreeze and allow loose wet snow avalanches to become possible. While most of these loose wet snow instabilities will manifest as small roller balls, pinwheels, and loose wet point releases, some of them could entrain enough snow to cause problems for backcountry travelers. Sun-exposed E-SE-S-SW-W aspects steeper than 35 degrees where the recent snow has not been through enough melt freeze cycles to create good drainage channels in the snow hold the best potential for loose wet avalanches today. In some areas where less new snow existed or where firm wind packed or scoured surfaces existed after the recent storm, the surface snow has already experienced enough melt-freeze cycles to become corn snow and loose wet snow instabilities may be less common on these slopes. 

    Sinking into wet snow above boot-top height, small surface wet snow instabilities like pinwheels or roller balls, and other recent loose wet snow avalanches can all indicate that enough wet snow exists for problematic loose wet avalanches to occur. These clues usually indicate that the snow conditions have become less fun to recreate on as well. At this point finding a more frozen aspect or switching activities represents a great way to stay safe and keep having fun. 

Avalanche Discussion

Daytime warming and sunshine created wet snow on sun-exposed SE-S-SW aspects by mid morning on Castle Peak (Donner Summit area), Gold Peak (north of Squaw), the west side of Carson Pass, and on Fireplug (Mt. Rose backcountry). On some exposed upper elevation slopes on Castle Peak, the west side of Carson Pass, and Fireplug that experienced more wind scouring and less snow during the recent storm, 2 to 6 inches of wet snow existed on top of a supportable firm surface. In these areas and on Gold Peak, deep wet, sticky, and punchy snow existed on other upper elevation slopes and on lower elevation or more sheltered slopes. Human triggered roller balls and pinwheels up to 3 ft in diameter occurred on Gold Peak and on Fireplug. Observations and tests on northerly aspects on Castle Peak and Fireplug showed a mix of firm wind packed surfaces and cold soft snow and did not reveal any signs of instability. 

Regioni coperte