Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Thu
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 8 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Very dangerous avalanche conditions will develop if this storm meets expectations. Avoid being on or under steep, wind-loaded slopes. Avalanches in the new snow will spread as places with bare ground get blanketed. Hitting obstacles remains a real hazard for riding and will increase the consequences of getting caught in an avalanche.  

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1.5–3

    Strong south winds accompany heavy snowfall with this storm. They’ll deposit thick, dense slabs on the downwind side of ridges and in gullies. At middle and upper elevations, where there was already snow cover, new slabs will develop on top of slick crusts, old wind board, or directly atop weak sugar snow. As new snow covers bare ground and the wind continues to redistribute snow, the problem will become more widespread.

    If new snow totals meet expectations today, large natural wind slab avalanches will become likely. Avoid being on or under wind-loaded slopes steeper than about 30 degrees. Poor visibility could make identifying that kind of terrain difficult. Getting swept through rocks and logs by an avalanche will have big consequences.

    (11/30/2025)

    A wind slab avalanche caught a rider and dragged them through rocks the last time we had significant wind-blown snow.

  • Storm Slabs

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

    Snow began falling last night as temperatures dipped. Precipitation has intensified this morning and will continue as temperatures rise a few degrees midday. The combination of intense snowfall rates and fluctuations in snow density could create storm slabs on steep sheltered slopes where new snow falls onto old snow. The problem will spread to more terrain as the new snow blankets bare ground. The overall trend of this storm is decreasing temperatures, and loose dry avalanches are also possible. 

    Feedback like shooting cracks in the dense new snow, and loose snow sluffing down very steep terrain are red flags that storm instabilities are developing. Be very cautious and choose mellow terrain if you’re venturing out in the storm and don’t want to get dragged through rocks by an avalanche. 

    (12/24/2024)

    Storm snow avalanche.

    Photo: Steve Mace

Avalanche Discussion

The avalanche forecast is heavily reliant on the weather. With new snow totals forecasted for 1 ½ to 3 feet across our whole zone, and strong winds, the avalanche danger is expected to rise quickly and remain elevated as more snow falls and blows onto leeward slopes. Most new snow will fall on bare ground or onto thin existing snow cover broken up by ground anchors. These areas will need some accumulation before avalanche problems develop.

Slopes on the northern half of the compass, above about 9,000 to 10,000 feet, had more continuous coverage pre-storm. Where new snow falls onto these slopes, wind and storm slabs will develop atop a variety of surfaces. Rain last weekend left a slick crust on the old surface in the Mammoth and June areas. It goes up to at least 11,000 feet on all aspects that had snow. In portions of the forecast area that did not get rained on, there was stiff windboard in the alpine, and weak facets in sheltered areas. The old snowpack, in general, was thin and composed of large loose facets interspersed with crusts.

Because this storm will be a base builder for large portions of the forecast area that had only dirt and rock until this morning, and because of the thin snow cover thus far this season, obstacles will be a major hazard for anyone traveling in the backcountry during the storm. 

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