Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

While natural activity will be less likely today, there has been little change in the potential for human-triggered avalanches. Weak snow at the base of the snowpack continues to be the primary concern. Recently formed wind slabs may still be reactive to human triggers and have shown the potential to “step down” to the ground. When in doubt, choosing travel routes with lower slope angles and without overhead hazard will limit your exposure.

Avalanche problems

  • Persistent Slabs

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

    Over the past 72 hrs, several large to very large avalanches were observed breaking to the ground. While natural activity will be less likely today, avalanches stepping down following a relatively small wind slab or resulting from human triggers remain likely. If triggered, the 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. Triggering one of these avalanches will be more likely in areas that have less snow. In areas with weak layers more than three feet below the snow surface, signs of instability may be less obvious, but the possibility of human-triggered avalanches still exists.  Persistent slab problems require persistent patience and extensive evaluation. Cautious route selection remains the most important strategy to manage this problem. Choosing travel routes with lower slope angles and no overhead hazard will limit your exposure.

    Large remotely triggered avalanche. North side of Dunderberg - N/NE Aspect 10400'

    Photo: High Sierra Snowcat

  • Wind Slabs

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

    Winds are expected to shift to the west-northwest today and continue at transportable speeds. Fresh slab formation is not likely to be substantial today; however, slabs that formed yesterday may still be reactive to human triggers. Blowing snow, recent drifting, and hollow drum-like snow surfaces are all signs that can clue you into nearby wind deposits. 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. 

    (1/24/2024)

    A remotely triggered hard wind slab avalanche broke in the recent storm snow and ran on an older wind slab. The crown started 6 inches deep and reached 2 feet deep across the slope. D1.5: about 80 ft wide and ran about 100 vertical feet. Did not step down to buried persistent weak layers.

    Photo: Eastern Sierra Avalanche Center

Avalanche Discussion

Recent Avalanche activity.

  • Yesterday’s brief storm and strong winds resulted in significant natural activity (D2-D3), including several sizeable persistent slab avalanches that are suspected to have started as relatively small wind slabs that “stepped down” into old snow.
  • Several human-triggered avalanches (D1-1.5) failing in the upper snowpack were reported in the Mammoth area, including at least two that carried riders down the slope. No injuries were reported.

Our recent loading events on 1-22 and 1-24 tipped the scales, bringing us past a notable threshold, both in the regional distribution of activity and in the size of resulting avalanches. Even small loading events continue to have an “outsized” impact on stability, resulting in significant avalanche activity and a spike in hazard that is very slow to fall. Keep this in mind if you decide to venture into the backcountry. Natural activity is less likely today, but the potential for humans to trigger a large and potentially deadly avalanche remains virtually unchanged.

Regions covered