Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
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

Large human-triggered wind slab avalanches remain likely today due to gale force winds and heavy snow across the forecast area. Today the avalanche danger is CONSIDERABLE in near and above treeline terrain and MODERATE in below treeline. Dangerous avalanche conditions exist. Carefully evaluate the terrain and snowpack before committing to any slope and use this information plan conservative travel routes that avoid the avalanche problems. 

Problemi valanghivi

  • Wind Slabs

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

    Strong winds and 12 to 20 inches of new snow in the last 24 hours have formed large wind slabs on wind-loaded aspects. The largest and most fragile wind slabs will exist on wind-loaded N-NE-E aspects and cross-loaded SE and NW aspects above 7500 ft. where the most snow has accumulated. Due to the strength of the wind and the changing wind direction between SW-S-SE, some wind slabs could exist in below treeline terrain as well as near and above treeline terrain on almost any aspect. More snow and wind across the forecast area today and lowering snow levels mean that wind slabs will continue to grow and become more widespread today. While the best window for natural wind slab avalanches likely occurred during the night, human triggered wind slab avalanches will remain likely on any wind-loaded slopes today.

    Looks for signs of recent wind loading such as cornices, blowing snow, wind drifts, wind pillows, ripples on the snow surface, and other wind created textures to help identify where wind slabs may exist and use this information to avoid these problematic wind slabs.

Avalanche Discussion

Yesterday observations on Tamarack Peak before the onset of heavy precipitation found evidence of widespread rain up to at least 9500 ft. and likely a bit higher. Refreezing rain crusts existed on all aspects and elevations. Some areas had small amounts of new snow on top of the crusts and the strong winds had already started to form small wind slabs by 11:00 am yesterday even though less than an inch of new snow had fallen by that time. Intense precipitation became widespread across the forecast area by 12:30 pm. yesterday. 

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