Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Conditions will change quickly as precipitation and wind increase this afternoon. Step back from steep, wind-drifted slopes as you start to see signs of instability like shooting cracks and collapsing in the snowpack. Give yourself a wide margin for uncertainty as buried weak layers get loaded by new snow.

A natural avalanche cycle could occur overnight and into tomorrow morning if the weather forecast verifies.

Problemi valanghivi

  • Wind Slabs

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

    New snow and strong southwest winds will build another layer of fresh wind slabs. Expect drifts to grow in size and sensitivity throughout the day. Watch for snow blowing across ridgelines and gullies and loading leeward slopes. Wind slabs can look rounded and textured, or sound hollow under your feet. Shooting cracks and collapsing in drifted snow are clear warning signs to dial back your terrain choices and stick to wind-sheltered terrain.

    (2/5/2025)

    Intense blowing snow in the Convict Lake area in the afternoon.

    Photo: Eastern Sierra Avalanche Center

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    Large to very large natural and remotely triggered avalanches failed on buried weak layers in the past 24 hours. Recent field observations from up and down the forecast area have noted poor structure and signs of instability, such as shooting cracks and audible collapsing in the snowpack. 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. Shooting cracks and 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. We expect loading from new snow and wind to exacerbate the problem this afternoon and overnight. 

    (2/5/2025)

    Large remotely triggered persistent slab avalanche near Virginia Lakes on 2/5/25.

Avalanche Discussion

A winter storm is expected to intensify throughout the day, with increasing winds and snowfall, which will raise the avalanche hazard. Dangerous conditions may develop before nightfall in areas that receive snow early. The storm is set to strengthen overnight, potentially triggering a large natural avalanche cycle into early tomorrow morning.

New precipitation will fall and drift onto dense snow from Tuesday’s storm. Surfaces this morning include graupel (which resembles styrofoam balls) and wind-packed snow on northerly slopes. There are slick crusts on south and west aspects hit by the sun or stripped by the wind. Layers of large sugary facets and facet-crust combos are buried a foot or more deep in areas north and south of Mammoth. They can be found more than 3 feet deep where winds have drifted the most snow onto shady aspects under cliff bands near the Sierra Crest, and on leeward slopes near treeline above about 9,000 feet. Feedback from these persistent weak layers can be inconsistent and a dangerous source of uncertainty. One thing is for sure: new loading will not make the problem go away.

Given the uncertainty of both the incoming storm and the snowpack, the best strategy is to make careful terrain choices, maintain a wide safety margin, and be prepared to retreat from steep slopes as conditions deteriorate.

    

 

  

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