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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Highlights

A small Wet Loose avalanche, a cornice falling, or the weight of a person could trigger a dangerous avalanche breaking deep within the snowpack. Choosing low-consequence terrain with low slope angles, avoiding slopes with hazards overhead, and maintaining wide safety margins are the best strategies for managing the avalanche problems.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3.5

    Persistent Slab avalanches are more sensitive to a person in the southern half of the forecast area and at lower elevations where the slab is thinner (3 feet or less). At higher elevations, particularly from Mammoth north, the slab is thicker (~4 to 6+ feet), and feedback may be unreliable. A very large avalanche could be the first sign a slope is unstable. A smaller wet loose avalanche, cornice fall, or the weight of a person in a rocky area with shallower snow cover, could be all that is needed to trigger an unsurvivable avalanche.

    Managing persistent slabs is difficult. They may be triggered remotely—from flatter terrain adjacent to steep slopes and from terrain people usually think of as safe. Persistent slabs often propagate widely and in unpredictable ways. Tracks on a slope do not mean that it’s safe. Shooting cracks and collapses are clear warning signs of the problem. However, feedback is often irregular. The best option is to minimize your exposure to steep terrain on the aspects and elevations with sugary facets buried under stiffer slabs. Use extra caution in rocky, complex terrain, near convexities, and on slopes with inconsistent snow depth.

    (2/20/2025)

    Large crown of an avalanche breaking in sheltered terrain that people often consider "safe."

    Photo: Marissa

  • Loose Wet

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

    Temperatures are forecast to rise well above freezing to about 10,500 feet today. Increasing clouds may limit solar warming and areas with wet surface snow. Assess the surrounding terrain for signs of wet instability in your area. 

    Rollerballs and pinwheels are obvious precursors of Wet Loose avalanches. Wet Loose avalanches can entrain heavy snow that is difficult to manage or escape from. Wet Loose avalanches can also trigger larger slab avalanches that break into deeper snow layers. The best way to manage Wet Loose avalanches is to travel when the snow surface is colder and stronger. Time your trips to avoid crossing on or under very steep slopes in the heat of the day.

    (2/19/2025)

    Small, intentionally triggerd wet loose avalanches on an east-facing test slope below treeline, late morning. 

    Photo: Eastern Sierra Avalanche Center

Avalanche Discussion

  • We are at the start of a spring-like warming trend. Temperatures dropped well below freezing overnight, but they should be about ten degrees warmer than yesterday. Some aspects that may see Wet Loose avalanches also have the persistent slab structure. A smaller surface avalanche could be enough to trigger buried weak layers. 
  • The last persistent slab avalanches ran on the 14th or 15th during the extreme wind event that closed out the most recent storm.  Strong southwest winds continued to load shady aspects with poor structure through mid-week. Shooting cracks and collapses on buried weak layers continued through at least Monday. Snowpack tests south of Mammoth continue to demonstrate the potential for facets and crusts to propagate a fracture across a slope. 
  • Southwest winds drifted snow onto north and east aspects through Wednesday. Recent drifts were very hard to trigger yesterday, with forecasters getting no results while stomping on a few near treeline test slopes. Cornices are perched on the ridges above shady slopes that have the persistent slab problem. Their roots could warm and weaken in the midday sun.
  • Avalanche conditions vary across our diverse forecast area. Differences in the structure of weak layers in the snowpack, and diminishing signs of instability are sources of uncertainty. Regardless, the consequences of an avalanche failing deep in the snowpack are incredibly high. 

Patience and disciplined terrain choices are the antidotes to an uncertain snowpack. Low slope angles and low-consequence terrain are the best ways to avoid triggering a deadly avalanche.

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