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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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The chance of natural and human-triggered avalanches will rise throughout the day. By late afternoon, increasing snowfall and strong to extreme southwest winds will build dense slabs at all elevations. Conditions will continue to deteriorate overnight and throughout the weekend.

Avalanche problems

  • Wind Slabs

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

    New slabs of drifted snow will grow in size and sensitivity as snow begins to fall. Hard drifts may bond poorly to underlying crusts and weak, faceted snow. Extreme winds could form slabs in usually sheltered areas. Use caution around mid-slope depressions, at lower elevations, and in forest openings. Leeward terrain features that typically encourage drifting - below ridgelines and the sidewalls of alpine couloirs and gullies -  will also become increasingly dangerous as slabs thicken across start zones. Cold wind chill values and potential whiteout conditions this afternoon could make that hazard difficult to assess. Plan to step back from steep slopes where blowing snow and growing cornices hint at the rising danger. 

    (2/28/2024)

    Large natural wind slab avalanche that broke on a usually sheltered slope near the bottom of a deep drainage near Lundy Canyon. This likely ran 2/26.

    Photo: Clancy Nelson

Avalanche Discussion

The strongest winter storm of the season will spread from north to south across the forecast area by late morning. The timing for the increase in avalanche danger will depend on how quickly new snowfall accumulates and drifts. Weather forecasts suggest up to 5 inches of new snow on the East Side by early evening, with higher amounts near the Sierra Crest. Exceptionally strong winds will drive new slab development at all elevations by this afternoon. Wind chills and whiteout conditions will complicate matters.

New wind slabs will likely be dense and hard. They’ll form atop crusts in exposed terrain and near-surface facets in typically sheltered areas, which could increase their sensitivity to human triggering. 

Snowpack depth and strength vary between drainages. Around Mammoth Lakes and areas to the north, the snowpack is over 5 feet thick. In the southern portion of the forecast area, the snowpack is closer to three feet deep. Several layers of sugary facets and crusts exist throughout the otherwise strong mid-pack. Depth hoar from the early season is still identifiable near the ground. These weak layers have shown improvements throughout February. However, with each major loading event, destructive avalanches have broken into old snow. Just three days ago, wind slabs stepped down to buried weak layers on McGee. The likelihood of a similar scenario will increase overnight and throughout the weekend. 

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