Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

A powerful storm will bring heavy snow and strong winds to our forecast region today forming slabs of wind blown snow.  Heavy loading of the snowpack with this storm will make larger avalanches possible that break deeper in the snowpack.  A period of HIGH avalanche danger is expected to occur this evening and overnight during high intensity snowfall.  Dangerous avalanche conditions will exist today as this storm impacts our region.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3

    Gale force South-Southwest winds will continue today forming wind slabs in near and above treeline areas.  Heavy and very dense wind slabs existed yesterday throughout the forecast region.  Another round of wind slabs will form today as this next storm impacts our area.  These wind slabs will form along ridges, in gully features, and in open areas.  Large and fragile cornices are built out along ridgelines and could collapse today.  Any large cornice collapse or large avalanche has the potential to step down into older and deeper weak layers in the snowpack creating very large avalanches.   

    Wind slab avalanches will become likely today.  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.  

  • Persistent Slabs

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

    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 incremental loading of the snowpack over the last week with multiple heavy wet storm events, these weak layers may be reaching their failure point.  Recent observations showing cracking and failures on these weak layers have become concerning. 

    As another large storm loading event begins today, large avalanches failing on persistent weak layers deeper in the snowpack will become possible.  Large loads like avalanches and cornice collapses would be the most likely triggers for today.  As this storm loads the snowpack with more weight, it's not out of the question that natural avalanche activity could occur on these weak layers during this storm.  Even with all the uncertainty, enough signs and evidence exist to take this problem seriously.  Any avalanches associated with this problem would be large and have severe consequences.   

    (2/5/2025)

    A ski kick caused a small car-sized piece of cornice to break and fall onto the slope below. This cornice piece triggered a failure that propagated along the slope for about 50 ft and caused two additional cornices above different test slopes to fail. Location: Far East Ridge of Tamarack Peak

    Photo: Sierra Avalanche Center

Avalanche Discussion

Uncertainty exists with snow levels rising with this storm and timing.  Snow levels are expected to increase this afternoon and evening as snowfall intensifies.  Rain could increase up to the 7000-7500' elevation range and maybe even up to 8000'.  Most of this is forecasted to occur in the early evening hours followed by a cooling trend into Friday morning.  If rain on snow occurs earlier than forecasted or at the higher elevation range, widespread wet loose avalanches and even wet slabs could occur on all aspects.  Wet snow problems could also extend slightly higher in elevation into areas where heavy wet snow falls instead of rain.  

Regions covered