Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Sun
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Widespread, large, dangerous avalanches are very likely today due to the intense rain, snow, and wind impacting the region. Avalanches are likely on any slope and all elevations, even sheltered below treeline terrain, which people often consider safe. Travel in, near, or below avalanche terrain is not recommended. 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–2.5

    Widespread, large, and destructive avalanches are likely today. 

    This powerful storm brings gale-force winds, intense snow, rising snow levels, and rain. Cohesive wind slabs and slabs of new snow have formed on top of old, weak snow, resulting in dangerous avalanche conditions. Unstable snow will exist at any elevation where new snow accumulates. In fact, the weakest old snow exists in the sheltered below treeline terrain, which people normally consider "safer," especially in the eastern and southern parts of the forecast area.  Avalanches could break wider than expected, or people might trigger them from below or while approaching these slopes.

    In areas where wind-blown snow has filled in the downwind side of ridges, gullies, and open slopes, larger unstable slabs of locally deeper snow will exist. Unstable slabs of storm snow will also form in areas without the old weak snow below since the storm snow will accumulate faster than it can bond to itself and will keep getting heavier as snow levels rise. 

    In summary, all slopes will be dangerous today.

     

  • Loose Wet

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

    Heavy rain up to 8000 or 9000 ft today will result in unstable, deep, wet snow on all aspects near and below the rain line. Wet snow problems will also extend slightly higher into areas where heavy wet snow falls instead of rain. Expect widespread wet loose activity as wet snow slides downhill. Long, steep slopes can produce large, dangerous, wet loose avalanches since they entrain more and more snow as they move. The heavy, wet snow/rain could cause the old, weak surface snow below it to break, resulting in slab avalanches of wet or storm snow, especially on protected northerly aspects where soft snow lingered during the dry spell. 

    (12/16/2024)

    Wet loose avalanche triggered by rain on snow on Emerald Bay Road from earlier this season.

    Photo: Sierra Avalanche Center

Avalanche Discussion

Today's travel advice is simple: avoid traveling in, near, or below avalanche terrain. An easy way to do that is to pick a different activity that does not involve recreating on the snow. Such activities may have the side benefit of keeping you drier as well. That being said, if you choose to go out into the rain, snow, and wind today, here are some things to consider. Pay extra attention to the terrain you travel in, even simple terrain. Stick to flat or very mellow slopes or trees so dense they are hard to move through. Use maps and observations to ensure you are not in or even close to the runout zones of any potential avalanche paths. Poor visibility may make figuring out what is above you much harder today. Remember that you don’t have to be on a steep slope to be struck by an avalanche that starts from above you. Small terrain features that may seem benign, such as roadcuts or creekbeds, could also be dangerous. 

Regions covered