Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Continued high winds with blowing snow could make wind slab avalanches possible today.  Strong sunshine and warming temperatures could also create areas of wet snow instabilities on slopes that receive direct sun.  Use caution near steep sunny slopes and areas where recent wind drifted snow has accumulated.

Problemi valanghivi

  • Wind Slabs

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

    Continued strong to gale force NE winds will move any available snow and continue to build wind slabs in near and above treeline areas.  New wind slabs yesterday were up to 1' deep and could remain fragile.  Wind slabs that have formed on SE-S-SW-W aspects could become weaker today and fail as rapid warming occurs with intense solar radiation.

    Look for blowing snow and signs of previous wind transport.  Exposed areas are scoured down to previous firm crusts from the recent NE winds.  New cornice formation, wind drifts and pillows, and snow surface clues should help to identify where wind slabs have formed. 

  • Loose Wet

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

    A combination of increased sun angles in February, solar radiation and increasing temperatures from a sunny day, and new snow, will make loose wet avalanches possible today.  These loose wet avalanches may start off small early this morning with roller balls and pinwheels, especially around rocks and gully features.  As solar radiation and temperatures increase as rapid warming occurs, these avalanches could become larger involving all the recent storm snow we received yesterday.  Areas that received the higher end of snow totals yesterday will have the potential for more consequential loose wet avalanches.  

    As rapid warming occurs this morning, it's time to move off of avalanche terrain or move to a different aspect that does not have direct sun.  Roller balls and pinwheels will be indications that the new surface snow is warming up and strength is decreasing-larger loose wet avalanches could follow.  Use good timing and manage aspects to stay ahead of the sun or avoid slopes with full solar radiation.

Avalanche Discussion

  • Snowmelt has sped up over the last two weeks exposing more obstacles (rocks, bushes, etc) and areas of bare ground on SE-S-SW aspects.
  • Under yesterday's new snow, highly variable old snow surfaces exist including smooth firm surfaces, rough uneven surfaces, soft weak snow, melt-freeze crusts, and everything in between. 
  • Gradual near-surface faceting has created weak snow in the top portion of the snowpack on many wind-protected and semi-wind protected NW-N-NE aspects. Yesterday's new snow will bury this weak layer but should not add enough load to break it in non-wind-loaded areas. 

Regioni coperte