Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

New snow and strong winds will form slabs of wind blown snow along ridges, in gully features, and in open areas.  Areas of loose snow may slide downhill on steeper slopes.  Dangerous avalanche conditions could exist today with large avalanches in the backcountry, avoid steep avalanche terrain where these problems exist.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    The recent storm snow is being transported by gale force SW winds in near and above treeline areas.  These wind slabs have been forming along ridges, in gully features, and in open areas.  With the recent storm snow to work with, these wind slabs are expected to be large in size and potentially over several feet deep.  Most of these wind slabs exist over the top of a firm rain crust surface along with other deeper weak layers in the snowpack.  Snow levels have varied greatly over this recent storm cycle with rising and falling rain levels.  This has put an additional very large load on our snowpack.  Large cornices are also expected to have formed over the last couple days and these could remain weak with the potential of collapsing today.  

    Large wind slab avalanches could occur today.  There is the potential for any large avalanche to step down into older and deeper weak layers in the snowpack.  Look for recent avalanche activity, blowing snow, and large cornices above a slope as clues as to where these wind slabs exist.  Avoid steep wind loaded slopes, areas below large cornices, and avalanche run out zones today.  

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Areas of dry loose sluffing are expected to occur in steeper near and below treeline areas today.  In areas where deeper snow exists, these dry loose avalanches could run downhill on steep continuous slopes, accelerating fast and running far distances.  Any natural point releases in steeper terrain will be a good indication that dry loose avalanches are likely.  Even though some of these may remain small in size, riders could be carried into terrain traps or over cliffs. 

Avalanche Discussion

The past 2 day storm cycle has brought a large load of rain and snow to our forecast region.  We have been dealing with a weak upper snowpack in the majority of our forecast area that formed during our dry January.  Deeper snowpack weak layers near the ground have been isolated to the far eastern and southern portions of the forecast region where a much more shallow and weaker snowpack exists.  With the additional wet heavy snow and rain, uncertainty exists about how much load these weak layers can take before they fail.  Much larger avalanches involving deeper weak layers in the snowpack, potentially even near the ground, cannot be ruled out at this point.    

Regions covered