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

In sintesi

Through the morning hours, avalanche danger will be Low on all aspects and elevations.  As daytime warming occurs, avalanche danger will rise to Moderate on E-SE-S-SW-W aspects on slopes steeper than 35 degrees due to the possibility of loose wet avalanches.  Isolated areas of loose wet instabilities may also form on NW-N-NE aspects. 

Problemi valanghivi

  • Loose Wet

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

    A stronger snow surface refreeze is expected to have occurred overnight with slightly colder overnight temperatures and reduced cloud cover as compared with yesterday.  Strong SW winds could delay snow surface warming in the most wind exposed areas near and above treeline although little to no delay will occur in more wind protected areas.  Wet snow instabilities are expected to form on E-SE-S-SW-W aspects on slopes steeper than 35 degrees during the late morning and through the afternoon hours as daytime warming occurs.  Wet snow instabilities could also occur on NW-N-NE aspects in the form of roller balls and/or pinwheels.

    Timing is critical to avoid loose wet instabilities and find supportable snow with the best travel conditions.  Recent roller balls or pinwheels are an indication that the snow surface is loosing strength and that loose wet avalanches are becoming possible.  Use boot penetration to constantly monitor the supportability of the snow surface.  If boot penetration exceeds 10-12 inches into wet snow, it's time to move to a less sun exposed aspect and/or terrain under 30 degrees without steeper terrain above.

Avalanche Discussion

Observations from Jakes Peak (West Shore) and Mt. Judah (Donner Summit) showed similar spring type conditions.  Wet surface snow existed by the late morning hours in wind protected areas and slopes below treeline.  Melt freeze crusts existed on SE-S-SW aspects and good corn snow was found in some areas.  The SW winds only slightly delayed snow surface melt in the most wind exposed areas.  At both locations, the overnight refreeze was moderate, with SE-S slopes below 7500' becoming unsupportable by mid day.  On Jakes Peak, roller balls and pinwheels were reported on NE and E aspects in the mid day hours.  Upper elevation east aspects are still transitioning with a few inches of wet snow on top of older snow.

Regioni coperte