Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Tue
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

An atmospheric river is bringing 4ft of snow to the Eastern Sierra today and tomorrow.  Very large avalanches will likely run into low-angle terrain below treeline. Even relatively small slopes above terrain traps could be dangerous today. Travel in and below avalanche terrain is not recommended.

Avalanche problems

  • Wind Slabs

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

    South winds will carry snow across ridgelines and drift it onto northerly aspects and leeward terrain features. Wind-transported snow can accumulate and overload the snowpack much more quickly than storm snow alone. Very large natural avalanches are expected today in leeward avalanche paths that sit just below ridgelines near and above treeline. It's important to avoid the runouts of large avalanche paths. With good coverage at lower elevations, very large natural avalanches could run down to valley floors and into low-angle below treeline terrain.

    (1/2/2023)

    Evidence of recent avalanche activity on Laurel Mountain - 20230102

  • Storm Slabs

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

    Snowfall rates greater than 2" per hour are forecasted for this storm and could lead to instabilities within the storm snow. With up to 2 feet of new snow expected today storm slabs will be large enough to bury a rider.  While storm slabs will be widespread at treeline and below treeline, they are most likely to release on steeper slopes (greater than 35 degrees) at convex rollovers in the terrain. These avalanches will be most dangerous today on slopes that end in terrain traps.  Avoid flat benches or gully features where snow from slopes and banks above you could pile up and create a deep burial. Terrain features that are normally considered too small to pose a threat may become dangerous today. The best way to manage storm slab hazards today is to stay out of avalanche terrain altogether.

    Beware of roof avalanches in mountain communities above 7000'.  

    (12/30/2022)

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–3.5

    Heavy snowfall and wind loading will test the strength of persistent weak layers at the base of the snowpack. Three weeks of cold clear weather in November formed a layer of faceted snow on NW through E aspects at all elevations. Subsequent storms have buried this layer 4 to 10 feet below the snow surface. At this depth, the deep persistent slab is unlikely to be triggered by a person. However, during the recent loading events natural avalanches have stepped down and released at the base of the snowpack. If triggered, deep slabs can propagate around terrain features that would otherwise confine new snow instabilities creating larger-than-expected avalanches. The possibility of these larger avalanches is another good reason to stay out of the run-outs of major avalanche paths.

    (1/2/2023)

    D3 avalanche triggered with explosives by the June Mountain Ski Patrol on 20230101. Avalanche failed on wet facets at the base of the snowpack..

Avalanche Discussion

The snowpack is now over a meter deep down to 7000' in many areas. This means there are smooth sliding surfaces and snow that can be entrained in the tracks and runouts of avalanche paths. Natural avalanches may run farther than expected today. In each of the previous major loading events, we have seen evidence of natural avalanches stepping down to older snow layers creating very large and destructive avalanches.

Deep snow also brings increased tree well danger. If out in the backcountry (or off trail at a ski area) make sure you keep sight of your partner.

Regions covered