Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Fri
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
4 · Forte
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In sintesi

An Avalanche Warning is in effect until 7 am Friday.

Very dangerous avalanche conditions are expected at all elevations as intense snowfall and strong winds continue to impact our area. Natural avalanches large enough to bury you are likely. Avoid being on or under slopes steeper than about 30 degrees. 

Problemi valanghivi

  • Wind Slabs

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

    Strong southwest winds continue, along with heavy snowfall today. Thick, dense slabs will grow on the downwind side of ridges and in gullies. Wind slab avalanches reported yesterday were running surprisingly far downslope. They’ll be bigger today and could run down into sheltered terrain. Poor visibility could make identifying that kind of terrain difficult. Avoid being on or under wind-loaded slopes steeper than about 30 degrees.

    (12/24/2025) Small wind drifted road cut, triggered remotely from snowcat. Visibility not great for other observations.

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    1–2.5

    Storm instabilities, both slabs and sluffs, will grow in size and become more sensitive as the day progresses. Large avalanches failing within the new snow will become increasingly likely in all areas. Over 40 inches of snow has fallen thus far, and snowfall rates of up to 4 inches per hour are forecast for most of today. Fluctuations in snow density could create storm slabs on steep sheltered slopes. The problem will be more widespread now that there is ample snow to slide on. Avoid being on or under slopes steeper than about 30 degrees. As significant snow accumulates in mountain communities, be aware of overhead hazards from roofs and road cuts in town.

    (12/24/2025) Shooting cracks from my hand Photo: Greg Cunningham

Avalanche Discussion

Santa has left a huge haul under our collective tree this year. And on top of the tree. And all around the tree. The first day of the ongoing storm exceeded expectations, with storm totals this morning topping 43 inches in favored areas like Mammoth. Across the forecast area, places that had shallow snow cover broken up by ground anchors, or were just bare ground, are now covered in white. 

Yesterday, several natural and remotely-triggered wind slab avalanches were reported on northeasterly, near-treeline terrain in the northern part of the forecast area. Avalanche forecasters trenching through deep snow below treeline in June Lake saw widespread shooting cracks at various interfaces within the storm snow. A natural loose snow avalanche ran below treeline near Aspendell in Bishop Creek. With all that instability, and mountain travel so difficult, we have not had any observations from higher elevations. However, it's not hard to extrapolate to higher terrain with all the feedback the new snow has given us from near and below treeline.

The new snow will take time to stabilize and avoiding avalanche terrain is the safest way to enjoy a whie Christmas.Besides bare ground, all this new snow has fallen onto a variety of old surfaces and snowpack structures. Slopes on the northern half of the compass, above about 9,000 to 10,000 feet, had more continuous coverage pre-storm. 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.

Regardless of the situation near the ground, the mountains will continue to get pounded by new and drifted snow today. Avalanches will have more snow to slide and more terrain to slide on. The new snow will take time to stabilize, and avoiding avalanche terrain is the safest way to enjoy a white Christmas. 

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