Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

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

Dangerous avalanche conditions will be driven by the size and sensitivity of newly formed wind slabs. These will be larger and more reactive at higher elevations where snow is drifting onto steep, leeward terrain. Buried weak layers continue to produce avalanches that release with little warning. Limiting your exposure to overhead hazards, convexities, and slopes with drifted snow is the safest bet while traveling in the mountains today.

Avalanche problems

  • Wind Slabs

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

    Increased wind transport will likely cause unstable wind slabs in steep leeward terrain. These will be larger the higher you climb. Specific features of concern include steep slopes below ridgelines, the sidewalls of gullies, and cross-loaded depressions. Recent avalanche activity, cracking within the surface snow, blowing snow, and hollow upside-down feeling snow, are all clues that wind slabs may be unstable in your area. If triggered, avalanches could propagate widely, breaking above or around your skis, board, or machine. Beware of your exposure to wind-loaded terrain above.

    (3/31/2023)

    Small natural avalanche in Redcone bowl triggered by direct wind loading. 3/31/23. N, 10,300'.

  • Persistent Slabs

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

    Cold clear nights in the short windows between our most recent storms have created thin sun crusts and weak layers of near surface facets at various depths within the upper snowpack. These are most likely found on slopes that combine sun exposure and wind loading. A stabilizing trend in the weather and settling surface snow may give a false sense of stability. Feedback may be limited and many recent avalanches have been triggered remotely without prior warning. Persistent slab avalanches can propagate beyond terrain features and connect several start zones. They can be triggered from below or from flatter terrain adjacent to steep slopes. You can manage uncertainty by maintaining a healthy distance from convexities, wind-loaded terrain features, and suspect slopes. Be aware of terrain like that above you.

    (3/31/2023)

    Large remote triggered avalanche in V-Bowl, Lee Vining area, 9000', 3/31/23

  • Loose Wet

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

    Temperatures will be notably warmer and wet loose avalanches will be possible by midday. In areas where the sky is clearest, winds are lightest, and freezing levels rise near 10,000 feet, areas of unstable wet snow will be more likely. Watch for rollerballs and small sluffs on sunny slopes as the first sign that wet loose avalanches are becoming a hazard. Rocky chutes, vegetated slopes, and areas with shallow snow cover will be the most concerning. Move to shady slopes if the surface snow thaws causing you to sink into deep wet snow. 

    (3/31/2023)

    Small loose wet avalanche near treeline on a south-facing slope in Lee Vining Canyon

Avalanche Discussion

  • Skiers remotely triggered a large slab avalanche at 9000 feet on an east aspect in V Bowl yesterday, 3/31. It likely failed on a crust/facet combo buried on March 29th. This is the latest in a long string of natural and rider-triggered slides failing on weak old snow atop crusts. Most of the activity has been concentrated near treeline on southeast, east, and northeast aspects. Many of these have been triggered from adjacent slopes. On the 29th, a very large natural avalanche released mid-storm on a northwest aspect at 11,400 feet on Bloody Mountain. The crown appears to connect around multiple terrain features. This avalanche also likely failed within the old snow.
  • Crust/facet combinations exist on west through north through southeast aspects at all elevations. The upper layer is typically 20 to 40 cm below the surface and the older layer (buried 3/19) is between 70 cm and more than a meter deep. Slabs releasing on these interfaces have most often been wind-deposited. There are high levels of uncertainty surrounding these layers because they have given inconsistent feedback, even on slopes adjacent to remotely-triggered avalanches.
  • Yesterday, 3/31, a natural wind slab avalanche occurred on a north aspect near the top of Red Cone Bowl. Winds outperformed the forecast and, in favored areas, observers reported wind loading and cornice growth on alpine ridges throughout the day. Winds have been steady overnight and are forecasted to increase slightly today.
  • Some loose wet avalanche activity occurred each afternoon for the past 2 days. Today will be an interesting mix of clearing skies, rising temperatures, and increasing winds. You’ll need to do your own localized assessments to track surface warming in your area. 

With good coverage at lower elevations this winter, avalanches have been running further, impacting roadways and buildings in mountain communities. It is important to practice good run-out awareness. Triggering an avalanche above infrastructure could have devastating consequences. Road crews are working overtime to allow access to communities that have been stranded by heavy snow, avalanche activity, and flood damage. Parking in areas where plows and road construction crews are operating can make it difficult to do the necessary work.

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