Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Wet instabilities may exist on all aspects and at all elevations today. Expect any surface freeze to soften rapidly, and for the snow to become wet and unsupportable. Consider overhead hazards and reduce your time spent traveling on steep slopes with wet snow on the surface. 

Avalanche problems

  • Loose Wet

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

    Yesterday, we recorded 4 fresh, small, natural avalanches on both northerly and southerly aspects. Temperatures are inverted this morning, and it did not drop below 40°F at the summit of Mammoth overnight. Today, temperatures are expected to be even hotter than yesterday, and any surface freeze will melt rapidly. As the surface freeze thaws, and the snowpack becomes wet and mushy, wet loose avalanches will become increasingly likely on all aspects and at all elevations.

    Be especially careful in areas where you're finding recent natural avalanches or seeing rollerballs. For the most part, these avalanches are likely to be small, but in isolated places, you may be able to trigger a consequential, large wet loose avalanche. The best bet to avoid this problem is to reduce time spent traveling on or under steep terrain with wet snow on the surface. 

  • Wet Slabs

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

    Over the past 3 weeks, our snowpack has melted a lot. Most sunny aspects at all elevations have had meltwater percolate through old, buried, weak layers. Generally, the snowpack on the southern half of the compass and at low elevations consists entirely of crusts and melt forms. The north half of the compass, at middle and upper elevations, is different. On shady aspects, the top 12-24” is settled and dense, but below that, dry snow exists. Prior to 3/16, observations noted dry facets midpack, preserved and intact.

    Uncertainty remains as to whether these preserved weak layers may “wake up” as meltwater again descends through our snowpack. These avalanches are hard to predict, and until we dial in a bit more confidence around this problem, it's worth reducing your exposure to steep terrain with wet surface snow, especially on the northern half of the compass at middle and upper elevations.

Avalanche Discussion

Abnormal weather conditions make for abnormal avalanche hazards. Wet slab avalanches have returned to the menu because this outlier warming event is unprecedented, and we are uncertain how our snowpack may adjust to the surge of meltwater percolating through it. 

The first thing you will likely encounter if you head out today is a lack of snow or patchy coverage at low elevations. If your trip plan involves crossing any creeks, they are likely running at high levels and lack any supportable snow bridges. Once you reach consistent coverage, you will likely encounter deep, wet snow. It may be unsupportable and downright dangerous to attempt to move through. If you manage to find some supportable travel, keep in mind that the surface may soften and become unsupportable as the day warms. Today is a tricky day to travel in the mountains. Think ahead and plan to spend your day managing more hazardous travel and avalanche conditions than in recent days.

Regions covered