Bulletin d’avalanche

Eastside Region

Eastern Sierra Avalanche Center
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Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 8 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Avalanche hazard increases as you gain elevation into terrain affected by the wind. Cornices, fresh dunes, and cracking on the surface indicate areas of concern. You can reduce your odds of triggering an avalanche by avoiding stiff wind-drifted snow. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–3

    The leeward sides of ridgelines, cliff bands, and cross-loaded gully features are conducive to capturing wind-transported snow and warrant careful evaluation.  Surface clues, such as recent cornice development, fresh dunes, and a stiff and hollow feeling surface, can clue you into areas that may have seen recent loading. This problem will be easy to spot and avoid.  If you feel the surface becoming stiffer, move to less consequential terrain. 

    On northerly aspects near and above 10,000', faceted old snow exists near the ground. While it's unlikely for a human to trigger an avalanche at the base of the snowpack, a wind slab avalanche has the potential to step down to deeply buried weak layers near the ground, creating a very large and destructive avalanche.

    (2/20/2025)

    Cornice hanging over a near treeline slopes.

    Photo: Clancy Nelson

Avalanche Discussion

Our surface problems are generally on a stabilizing trend and are becoming less reactive to human triggers. As a result, we have removed the storm slab avalanche problem. While it is still possible to trigger a wind slab avalanche at upper elevations, it's worth considering the structure deeper in the snowpack.

Numerous large to very large avalanches were observed at upper elevations across the forecast zone yesterday. Our neighbors to the north at the Bridgeport Avalanche Center reported multiple avalanches failing in faceted snow near the ground. Two very large (D3) avalanches were triggered by snowmobilers in the Leavitt Lakes area on 12/27. Of the riders involved, one sustained serious injuries. The slopes the riders were traveling on had retained old snow buried beneath our most recent load.

In northerly terrain near and above 10,000', old snow lingered before this storm cycle; a large slab of new snow now sits on top of it. A north-facing aspect near the Mammoth Crest illustrated this structure well. Roughly 75 inches of firm, settled new snow overlayed a rain crust from early in the week. Beneath that crust, decomposing weak facets formed the base of the snowpack. We still have a lot of uncertainty surrounding this structure, its distribution, and its sensitivity across our terrain. A lack of observations reinforces a low likelihood, high-consequence hazard. It is unlikely for a skier to trigger a very large avalanche on facets below our new load; however, if you trigger a wind slab, it may be possible to step down to this deeply buried weak layer. The result will be a very large and destructive slide, powerful enough to push a car off the road. To help manage this structure, limit your exposure to avalanche terrain and avoid steep wind-loaded slopes.

Régions couvertes