Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

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

In sintesi

More precipitation occurred than forecast over the past 24 hours, with rain on snow extending into upper elevation terrain. Triggering a wet snow avalanche is possible today in a variety of areas. Triggering a slab avalanche is possible in upper elevation terrain that has been filled in with wind drifted snow.

Problemi valanghivi

  • Loose Wet

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

    Significantly more rain occurred than forecast over the past 24 hours. Air temperatures below 9,000' remained above freezing last night at nearly all locations within the forecast area. Air temperatures in the 40s are expected today in most area. Slopes that hold wet snow on the surface today will be prone to wet loose snow avalanches. Some areas may have a frozen rain crust on the surface, but many will not.

    Some natural wet snow avalanches may have occurred late yesterday afternoon or yesterday evening. Wet loose avalanches triggered by backcountry travelers remain possible today. Use clues such as wet surface snow, rollerballs, and pinwheels to highlight areas of concern for this avalanche problem. Move around steep slopes with caution in areas where wet surface snow exists.

    (12/16/2024) An example of wet loose avalanche debris is steep, low to mid elevation terrain, Emerald Bay, CA.

    Photo: Sierra Avalanche Center

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Some small wind slabs may exist near ridgetops, in gullies, or on open slopes that are more filled in than surrounding areas with wind drifted snow. Above treeline and near treeline terrain near or above yesterday's rain line are where this avalanche problem is most likely to be found.

    Slopes below cornices and wind drifts are the main areas of concern. Move around these areas with caution.

    (1/1/2025) A car sized block of cornice broke off yesterday afternoon, triggering a shallow wind slab avalanche. NE aspect terrain along the Sierra Crest to the south of Mt. Lincoln, Donner Summit area, CA

Avalanche Discussion

There is a fair bit of uncertainty as to how high it rained yesterday afternoon and evening. Reports of freezing rain up to at least 8,300' in the Donner Summit area combined with weather station data around the rest of the forecast area suggest rain occurred as high as 8,500' to 9,000'.

On Dec 30th, possible buried surface hoar was observed within the top 8 to 12 inches of the snowpack in isolated locations in the Ebbetts Pass and Carson Pass areas. There is a small chance that a shallow but wide avalanche could be triggered in an isolated area where buried surface hoar exists.

Regioni coperte