Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You may see fewer signs of instability today, but the potential for dangerous avalanches failing at the base of the snowpack remains. Carefully planning your route before leaving the trailhead can help you avoid steep terrain where avalanches are most likely. The avalanche danger will rise steadily starting tonight as a series of winter storms move into the area.

Avalanche problems

  • Persistent Slabs

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

    Persistent slab avalanches can be triggered from below a steep slope or from adjacent slopes. These avalanches can propagate long distances and beyond terrain features that typically contain surface instabilities such as storm or wind slabs. If triggered, the resulting avalanche could break with little warning, involving the full depth of the snowpack. Managing this problem is made more difficult because of our shallow and inconsistent snow coverage. The few areas with enough snow for backcountry riding are generally the same areas where the avalanche problem exists. Feedback in terms of signs of instability may not be as obvious today, but the potential for a human-triggered avalanche remains. To limit your exposure to persistent slab avalanches look for travel routes with slope angles less than 30 degrees and without overhead hazard.

    (1/17/2024)

    Large natural avalanche. NE aspect, 10,800', Mammoth Lakes Basin. Likely released overnight between 1/16/24 and 1/17/24.

    Photo: Everett Phillips

Avalanche Discussion

Strong winds following the last storm and two days of warm temperatures mean there is less snow available for transport.  If you are out in the mountains today, look out for evidence of blowing snow and wind loading in leeward terrain. These are indications that the avalanche danger may be rising ahead of schedule. It is a good idea to build options into today's plan in case the storm arrives earlier than expected.

Recent avalanche activity: Multiple natural wind slabs and persistent slab avalanches released on N, NE, and E aspects near and above treeline overnight from 1/16 to 1/17. 

Snowpack Summary: We are currently tracking two persistent weak layers (1) a  layer of small to medium-grained facets down 40 to 90 cm; and (2) Advanced facets and depth hoar buried near the ground down 60 to 120cm.  Either of these layers may become the primary layer of concern depending on aspect, elevation, and wind-loading patterns. Variation in snow depth near and above the treeline has led to larger slabs with weaknesses at their margins and around trigger points in shallower areas. Digging and probing as you travel through terrain will help to track the presence and depth of these layers. 

There are two main sources of uncertainty in today's forecast; (1) Persistent slab avalanche forecasting is inherently uncertain. (2) Winds this afternoon may be stronger than expected and snow in fetches may be more susceptible to transport than expected. This could lead to wind-loading on leeward slopes and a faster-than-expected rise in avalanche hazard this afternoon and evening.

Regions covered