Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Tue
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

Dangerous avalanche conditions are expected to develop today as a potent winter storm brings new snow and strong winds to the region. Natural and human-triggered avalanches will grow in size and become increasingly likely as the day progresses. Monitor for changing conditions and be ready to retreat to more simple terrain without overhead hazard as the storm intensifies.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–2

    Fresh wind slabs will grow in size and sensitivity throughout the day as new snow and strong southwest winds impact the forecast area. Expect areas of unstable snow to be larger and more sensitive as you gain elevation. Blowing snow and growing cornices will point to the most dangerous slopes. Stiff, textured drifts could fail naturally and break widely under ridgelines and on the sidewalls of gullies. Poor visibility will make it hard to assess the terrain above you. As snowfall rates and drifting increase, avoid being on steep wind-loaded terrain and in the runouts of avalanche paths. 

    (3/7/2025)

    Intentionally triggered D1.5 wind slab avalanche. Near treeline, east aspect.

    Photo: Eastern Sierra Avalanche Center

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    As today's storm accumulates, storm instabilities (condensed slabs and loose sluffs) will become likely in steep, sheltered terrain. Today’s storm is expected to bring heavy snow with rates over 1” per hour and total accumulations from 12-20"  in favored locations. Surface instabilities will grow in size and sensitivity throughout the day. Convex rollovers and steep, unsupported slopes will become areas to avoid as new snow accumulates.  It is also important to be aware of potential terrain traps, such as road cuts, gully features, cliff bands, and mid-slope depressions, that can increase the consequences of an avalanche.  

    (3/13/2025)

    Small storm slab avalanche on a steep rollover

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    No new avalanches have been reported on these buried weak layers in the days since last week’s loading event. However, today’s storm is expected to bring over 1” of water weight to the region, further stressing buried weak layers in our snowpack. While significantly less likely than surface instabilities today, the consequences of an avalanche breaking deep in the old snow will be very high.

    Managing persistent slabs is difficult. They may be triggered remotely—from flatter terrain adjacent to steep slopes. Persistent slabs often propagate widely and in unpredictable ways. Deep Shooting cracks and large 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, particularly in rocky, complex terrain, near convexities, and on slopes with inconsistent snow depth.

    Photo: Eastern Sierra Avalanche Center

Avalanche Discussion

A potent winter storm will bring increasing hazard today with peak instability expected overnight tonight. The largest accumulations are expected in the Mammoth area and at higher elevations along the Sierra crest. To what extent the avalanche hazard rises today will be largely dependent on new snow accumulations. If we see the high end of forecasted snow, avalanches large enough to bury you will become likely near and above treeline by early this afternoon. Either way, you can expect the size and distribution of potential avalanches to increase as snowfall rates intensify. If you decide to venture outside today, it will be critical to monitor the storm closely. Managing terrain and avoiding areas of unstable snow will become increasingly difficult as the day progresses. Watch for signs of instability and be ready to retreat to more simple terrain without overhead hazard as the storm intensifies.

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