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
1 · Debole
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Non aggiornato — questo bollettino è scaduto 7 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The avalanche danger remains MODERATE in near and above treeline terrain due to the possibility of lingering wind slab avalanche problems. Human-triggered avalanches large enough to have consequences may remain possible in some areas. 

Problemi valanghivi

  • Wind Slabs

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

    Leeward aspects (NW-N-NE-E-SE) in near and above treeline terrain still hold slabs of wind drifted snow. In most places, these wind slabs should be more difficult to trigger today, but the additional weight of a person might still release an avalanche in some areas. Complex or extreme terrain including couloirs, cliffy areas, unsupported slopes, and steep convex rollovers will be the most suspect. Wind slab avalanches could entrain enough snow to bury, injure, or kill a person. Large cornices exist along exposed ridgelines.

    Today, areas with more avalanche concerns correspond to areas with more variable and challenging snow conditions. Seeking out more sheltered terrain will provide softer more consistent snow with fewer avalanche concerns. Use clues like cornices above a slope, blowing snow, drifted snow, and other wind created surface textures to identify where wind slabs and wind-affected snow may exist.

Avalanche Discussion

Observations yesterday from the Mt. Rose backcountry, Yuba Pass, Donner Summit, Brockway Summit, and the Blue Lakes area all reported blowing snow and very large cornices along ridgelines.

On Incline Lake Peak yesterday, ski kicks triggered wind slab failures up to 12 inches deep on small test slopes. One observer also reported a small (4-6 inch deep) wind slab failure on Wildflower Ridge around 5 pm. On Yuba Pass, Andesite Peak, and Brockway Summit ski cuts on wind-loaded test slopes only produced minor cracking in shallow wind slabs and did not cause wind slab failures. 

Snowmobile slope cuts on some steep, more sheltered, N-facing test slopes in the Blue Lakes area did not produce signs of instability. Other observations from Yuba Pass, Donner Summit, Brockway Summit, and the Mt. Rose backcountry also did not see signs of instability in sheltered non-wind-affected terrain.

Sun crusts and wet snow were reported on southerly aspects on Brockway Summit and in the Blue Lakes area. 

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