Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Increasing winds today could cause blowing snow and form slabs of wind-blown snow in exposed areas.  Wet snow avalanches are possible on sun exposed slopes as daytime warming occurs.  Use caution while traveling in avalanche terrain and make a plan that addresses todays avalanche problems. 

Problemi valanghivi

  • Wind Slabs

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

    Winds shifted to the West yesterday afternoon and will increase in speed today.  Over the last several days, winds have been elevated and blowing from pretty much all directions strong enough to transport snow.  Near and above treeline terrain are a mix of wind scoured surfaces, hard wind slabs, and large wind features.  Just off ridges though, some areas of soft snow exists that could be wind transported today and continue to form wind slabs.

    Look for areas of blowing snow, cornice formation, and snow surface clues to help identify where new wind slabs may be forming.  Some of these existing wind slabs on E-SE-S-SE-W aspects may be weakened from intense solar radiation today.  

  • Loose Wet

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

    Many wet loose avalanches occurred yesterday throughout the forecast area.  Most of these avalanches were superficial involving a few inches of the surface snow, but some were much larger and ran longer distances.  Slightly cooler temperatures, along with increasing clouds and West winds may limit some warming from occurring today in some areas.  March solar radiation will still be intense on most slopes throughout the forecast region.  Wet loose avalanches are expected to occur today with up to size D2 possible.

    Sun crusts have formed on E-SE-S-SW-W aspects at most all elevations yesterday.  Once these crusts melt and the snow surface becomes wet, it's time to move away from avalanche terrain or change aspects away from the sun.  

    (3/2/2023)

    Photo was taken at 1:30pm and slide occurred before then.  Approximately 3000' length.  Minden Mile, Outside of forecast area.

    Photo: Public

Avalanche Discussion

Recent Observations:

  • A large natural avalanche cycle occurred during the end of the last storm cycle sometime on Tuesday or late Tuesday night.  Check out our observation page to see the many large natural avalanches that have been reported.  These avalanches all had deep crowns up to 4 to 8+ feet deep, wide propagation, and are all thought to have failed on the Feb 21 old snow surface.  This old snow surface in many areas was a melt freeze crust that formed with weaker faceted snow that developed below it. 
  • No avalanches have been reported or are thought to have occurred on the Feb 21 weak layer since the end of the storm on late Tuesday night.
  • Sun crusts have formed on E-SE-S-SW-W aspects at most all elevations.  Thin sun crusts are also forming on lower angle Northerly aspects.  Tree drippings and bombs have refrozen around and beneath treed areas.
  • The Feb 21 old snow/storm snow interface is now buried 6 to 10 feet deep in the snowpack in wind protected areas on some NW-N-NE aspects.  Some snowpack tests have shown weakness on this layer, but other signs of instability have not been present for multiple days now.  Due to the depth of this layer, the strength of the snow above, and the relative strength of the layer-avalanches are unlikely on a regional scale.

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