Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

It remains possible for humans to trigger a persistent slab avalanche at any elevation today or in areas you may typically think of as “safe.” Expect avalanche hazard to rise this afternoon as a quick-moving storm system enters the region. When in doubt, use terrain choice to limit your exposure by sticking to lower slope angles without overhead hazards.

Avalanche problems

  • Persistent Slabs

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

    Human-triggered persistent slab avalanches have been reported on a daily basis since our last loading event, and weak faceted grains within the old snow continue to show the potential for failure. If triggered, a resulting avalanche could break with little warning, involving the full depth of the snowpack. It will be possible to trigger a persistent slab avalanche from adjacent slopes today. Avalanches may propagate long distances, and beyond terrain features that typically contain surface instabilities such as storm or wind slabs. Managing this problem is made more difficult because of our shallow and inconsistent snow coverage. This means that the few areas attractive for riding are generally the same slopes where this avalanche problem exists. Cautious route selection remains the most important strategy to manage this problem. When in doubt, choose travel routes with lower slope angles and no overhead hazards to limit your exposure.

    1/14/24

    Human-triggered Persistent slab avalanche bellow tree line in the Horseshoe trees, Lakes Basin. - Mammoth Area

    Photo: Steve Mace

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    The last two days of relatively quiet weather and lower wind speeds have narrowed the areas with our wind slab concern to leeward catchment zones near and above the treeline. Older wind deposits put down during our last loading event on Jan 13th have become more stubborn to human triggers. Expect fresh windslab development this afternoon and into the evening as a quick-moving storm arrives. Do your own localized assessments and be suspect of terrain features that encourage drifting, such as the leeward sides of ridgelines, alpine couloirs, gully features, and cross-loaded depressions. It is critical to remember that the distribution of wind slabs overlaps with our persistent slab problem. This means that even a relatively small avalanche breaking in the upper snowpack has the potential to step down into older snow, creating a much larger and more destructive avalanche.

    Shooting crack within fresh windload

    Photo: Steve Mace

Avalanche Discussion

Not a lot has changed in the avalanche picture since yesterday. Our focus remains on the elevated potential for human-triggered avalanches breaking on persistent weak layers deep in the snowpack. A quick-moving storm is expected to add a fresh load to our weak snowpack this evening. This storm will not bring a big load by Sierra standards. However, it's important to remember that with a shallow and weak snowpack like ours, even relatively small storms can have outsized impacts on avalanche stability.  Conservative terrain choice remains the most effective way to deal with this uncertainty.

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