Bollettino valanghe

Central Sierra Nevada

Sierra Avalanche Center
Vedi sulla mappa

Pericolo valanghe

Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
Open full map
Non aggiornato — questo bollettino è scaduto 10 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Moderate avalanche danger exists on NW-N-NE-E-SE aspects near and above treeline on slopes steeper than 35 degrees due to ongoing wind slab problems.  As daytime warming occurs, moderate avalanche danger will also become possible on E-SE-S-SW-W aspects at all elevations due to loose wet avalanches.  Evaluate snow and terrain carefully, identify features of concern. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    3

    Natural and human triggered wind slab avalanches have occurred over the last couple days throughout the forecast area.  Gale force SW winds have built up large wind slabs that are slowly gaining strength.  Most windward slopes are scoured down to firm crusts with little additional snow available for winds to transport.  No additional wind slab development is expected although current wind slabs could still be reactive and human triggering remains possible.

    Identify and avoid steep wind loaded terrain. Use clues such as recent avalanche activity, test slope failures, blowing snow, cornice formations, wind pillows, snow surface scouring and shooting cracks to determine where wind slabs exist.

  • Loose Wet

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

    As daytime warming occurs, loose wet avalanches will become possible on E-SE-S-SW-W aspects on slopes steeper than 35 degrees.  Most of these instabilities should be in the form of roller balls and pinwheels and could be both natural and human triggered.  Depending on how much solar radiation and warming we receive today, some larger loose wet avalanches could become possible that could entrain enough snow to bury or injure a backcountry user.  Wet snow instabilities could also form on NW-N-NE aspects that are in the sun or at lower elevations.

     

     

Avalanche Discussion

A boarder triggered wind slab avalanche was reported in the East Gully on Waterhouse Peak yesterday.  The avalanche occurred at 9200' on an East aspect and was 50' wide, ran 200' downslope and was 1' deep.  A cornice collapse was also reported from the Donner Summit area and was skier triggered on a small wind feature.

Observations from Jakes Peak (West Shore area) and Powderhouse Peak (Luther Pass area) showed unstable snowpack test results but very little instability from test slopes and informal observations.  Gale force winds were moving large amounts of snow and scouring windward areas down to firm crusts.  Snow surface conditions were wind affected at all elevations with heavy and grabby snow reported.  Rain crusts were observed up to at least 7000'.

 

Regioni coperte