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

In sintesi

Early this morning, avalanche danger is LOW for all elevations and aspects. Avalanche danger will quickly increase to MODERATE danger by the late morning hours for all elevations and aspects in response to daytime warming. Small human triggered loose wet avalanches are expected today. Natural avalanche activity is unlikely but not impossible.

Problemi valanghivi

  • Loose Wet

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

    Overnight minimum air temperatures were well above freezing once again last night and skies were partly cloudy. Snow surface refreeze is expected to be fairly superficial again this morning, having been dependent entirely on weak radiational cooling. A few hours of supportable snow surface conditions are expected early this morning. Once the surface melt-freeze crust is no longer supportable, avalanche danger will rapidly increase. When dealing with wet snow instability, the transition from stable to unstable snow can occur in as little as 15 minutes. By late morning, daytime warming is expected to have caused sufficient snow surface melting to allow for human triggered loose wet avalanches to occur on all aspects.

Avalanche Discussion

Observations made yesterday on Tamarack Peak (Mount Rose backcountry) revealed that a poor overnight refreeze had occurred. The surface melt-freeze crust that had formed overnight was just 1.5 inches thick. Departing from the trailhead at 9:45am, 0.5 inch of wet snow existed on the snow surface in sun exposed areas at 8,650'. Conditions at that time were still skier supportable. At 10:40am wet snow boot penetration of 1 foot existed near the summit on an E aspect at 9,760'. Upon descending this E aspect at 11am, skier triggered roller balls 6 to 12 inches in diameter were triggered off of turns with conditions marginally skier supportable and degrading rapidly.

Regioni coperte