Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Sat
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

UPDATE: We have upgraded our Avalanche Watch to an Avalanche Warning. Rising snow levels and increasing precipitation has created widespread areas of unstable snow.

Snow and low elevation rain showers combined with extreme winds have created dangerous avalanche conditions throughout the forecast area.  Natural and human triggered avalanches are very likely.  Travel on, near, or underneath avalanche terrain is not recommended.

Avalanche problems

  • Wet Slabs

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

    As of the time of publishing, up to 3” of new snow has been recorded and the rain line has already begun to creep up. Precipitation rates are expected to increase throughout the day. Warm temperatures and rain on snow do weird things to the snowpack. The rain crust from Tuesday’s storm event will make for a good sliding surface, avalanches may initiate and run at lower slope angles, and you can expect snow from our last storm to become increasingly upside-down at lower elevations. Slab avalanches breaking at lower elevations today may act and feel like storm slabs. However, it will be possible for slabs to initiate deeper in the snowpack, producing more sizable avalanches then our new snow totals would suggest. Loose wet point release avalanches will also be likely today and water may percolate deeper in the snowpack with prolonged rain showers. It won't be out of the question to see avalanches breaking near the ground, particularly in areas with relitively thin coverage. Instabilities are expected to grow in size and to become more sensitive as the day progresses. Avoid being on or under terrain over 30° today and be cognizant of your exposure to terrain features that increase the consequences of an avalanche. This includes road cuts, gully features cliff bands, and mid slope depressions.

  • Wind Slabs

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

    Increasing snowfall and strong to extreme SW winds will create dangerous wind slab conditions on northerly and easterly terrain features, particularly near and above treeline. Expect the size and distribution of fresh sensitive wind slabs to grow today as strong winds and snow continue to impact the forecast area. Be suspect of terrain features that encourage drifting such as the leeward sides of ridgelines, gully features, and cross-loaded depressions.  Large  Natural and Human triggered avalanches are likely today.

    (12/28/2022)

    Crown line and bed surface of size 2 human-triggered wind slab in Redcone Bowl

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    On a regional scale, our persistent slab problem has become unreactive. However, our incoming storm will add significant stress to the lower snowpack. While unlikely, an avalanche breaking near the ground has the potential to be very large and destructive. Steep and unsupported slopes, areas with shallow trigger points, and areas with a generally thinner snowpack are areas to consider. Persistent Slabs challenge our patience and managing this problem requires extensive evaluation and deliberate terrain choice. Persistent slab avalanches often propagate across and beyond terrain features that would otherwise confine surface instabilities such as wind or storm slabs and in some cases persistent slab avalanches can be remotely triggered from adjacent slopes. Give yourself a wide safety margin, be wary of hazards that may reside above you, and use terrain choice to limit your exposure.

Avalanche Discussion

Extreme caution is advised if you decide to head into the backcountry today. The risk of large and destructive avalanches will become more likely as the day progresses.  Top of mind for the forecast team is the added load in the form of rain at lower elevations. Rain on snow almost always produces wet snow avalanches. The rain-snow line is expected to climb as high as 9,000 feet today and remain there through the evening.  It’s important to remember that wet debris is heavy and difficult to escape. Even small wet avalanches can be dangerous above terrain traps like cliffs or creek beds.  Give yourself a wide safety margin today, be wary of hazard that may reside above you, and use terrain choice to limit your exposure.

 

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