Boletín de aludes

Central Sierra Nevada

Sierra Avalanche Center
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Peligro de aludes

Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
Desactualizado: este boletín caducó 11 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Considerable avalanche danger exists on NW-N-NE-E-SE aspects at all elevations due to persistent slabs and newly forming wind slabs.  On S-SW-W aspects at all elevations Moderate avalanche danger exists.  Careful snowpack evaluation, cautious route finding and conservative decision making are essential today.

Problemas de aludes

  • Deep Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    Several layers of concern are present in our current snowpack that have developed over the last week.  These buried surface hoar layers exist on NW-N-NE-E-SE aspects in near treeline and below treeline terrain and should be buried anywhere from 4'' to 3' deep.  The incoming, wet and heavy storm will put additional stress and weight on these layers which could make them fail today.  There is high variability and some uncertainty as to where these layers exist throughout the forecast area.  These avalanches have the possibility to propagate large distances, be remotely triggered, and have high consequences. 

    This is a near treeline and below treeline avalanche problem and is not common for our area.  Any slopes that have buried surface hoar will be suspect.  Look for recent avalanche activity, shooting cracks, and whumphing noises.  Use careful terrain selection to avoid steep open areas near and below treeline.  

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2

    Dense and heavy wind slabs could form today as this winter storm affects our forecast area.  SW wind gusts are expected in excess of 100mph over the Sierra Crest.  Expect wind slabs to form on NW-N-NE-E-SE aspects near treeline and above treeline with the possibility of these winds slabs also forming below treeline in open areas.  With higher snow levels these wind slabs will be much more dense and heavy than the existing snow and could fail near the old snow/new snow interface. 

    Avoid wind loaded areas.  Look for blowing snow, cornice formation, wind pillows and snow surface scouring to help identify where these wind slabs are forming.

Avalanche Discussion

An avalanche was reported to have occurred in the Blackwood Canyon area in below treeline terrain.  This avalanche was snowmobile triggered, 2-3' crown line, and thought to have happened late Sunday.  The weak layer for this slab avalanche is unknow but the buried surface hoar layer is suspected in this type of terrain. 

Other recent observations across the forecast area show a well bonded and consolidated snowpack.  Yesterdays observations from Elephants Hump (Carson Pass area), West Grouse Rock (Ward Canyon area) and Little Truckee Summit (Independence Lake area) all showed no instabilities with snowpack tests and informal observations.  Surface hoar was observed throughout the day on Donner Summit and at Little Truckee Summit area.

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