Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
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Pericolo valanghe

Sun
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

High winds and blowing snow will add to the slabs of wind drifted snow in exposed areas along ridges and in gully features.  Areas of wet surface snow may form due to intense April sunshine and rapid daytime warming.  Use caution while traveling around areas where unstable wind drifted snow or wet snow exists.

Problemi valanghivi

  • Wind Slabs

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

    Strong to gale force winds will continue today blowing snow and building wind slabs on NW-N-NE-E-SE aspects in near and above treeline areas.  Wind slab avalanches have been reactive over the last few days with another wind slab avalanche reported yesterday.  Snow is available on ridges for wind transport which will allow for more blowing snow and wind slab development today.  Very large cornices continue to exist along ridgelines with a large cornice collapse reported yesterday.  If more sun and warming occurs today than forecasted, sun exposed wind slabs and cornices could weaken more than expected. 

    Wind slab avalanches will most likely occur below ridges and in gully features where blowing snow has been active and cornices have formed above slopes.  Identify where unstable wind slabs will exist and cautiously move around them.  Avoid areas below large cornices.    

    (3/31/2023)

    Wind slab avalanche snowboarder triggered on north side of Castle Peak, Donner Summit area.

    Photo: Public

  • Loose Wet

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

    Forecasted increasing clouds and strong to gale force winds should limit this avalanche problem for today.  Though some areas may see enough sun and warming for wet loose instabilities to form.  Most wet snow will form on E-SE-S-SW-W aspects, but could occur in other areas with the high April sun angles.  Roller balls and pinwheels will be indications that this avalanche problem is active.  Larger slopes could entrain more snow and produce larger wet loose avalanches.

Avalanche Discussion

  • Unstable wind slabs continue in some ridgetop areas.  A snowboarder triggered wind slab avalanche was reported on Castle Peak, in the Donner Summit area yesterday.
  • A large cornice collapse occurred in Ward Canyon yesterday.
  • Several inches of unconsolidated snow were observed yesterday along the ridgetops, available for transport as wind speeds increase.
  • Sun crusts have formed on most sun-exposed slopes across nearly all aspects.
  • Signs of persistent instability on graupel and crust layers across NW-N-NE aspects within the forecast area have become increasingly isolated and difficult to trigger. Triggering an isolated persistent slab avalanche 1.5 to 4+ feet deep in snowpack has become unlikely on a regional scale yet still not impossible.

Regioni coperte