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
4 · Forte
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Though snowfall rates peaked early last night, wind loading onto a snowpack with a weak base will continue to create very dangerous avalanche conditions today. Very large natural avalanches from above threaten the slopes below. Avoid being on or underneath steep terrain until the snowpack adjusts to the new load.

Problemi valanghivi

  • Wind Slabs

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

    Southwest winds increased overnight and will be strong into the early afternoon. There is ample new snow being blown onto leeward terrain creating large and sensitive drifts spanning whole start zones. Blowing snow and growing cornices will point to the most dangerous slopes. Stiff, textured drifts can fail naturally and break widely under ridgelines and on the sidewalls of gullies. Poor visibility can make it hard to assess the terrain above you. Avoid steep wind-loaded terrain and the runouts of avalanche paths below. 

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3.5

    Over 3 inches of new water weight and wind-drifted snow continue to overload start zones with persistent weak layers at the base of the snowpack. Hard slabs failing on these layers will involve the full depth and weight of the snowpack. Persistent slab avalanches can propagate beyond terrain features and connect multiple start zones. A wind slab or cornice fall could kick off a larger and more destructive avalanche. Ample new snow in the tracks and runouts mean that avalanches can run to lower elevations and into lower-angled terrain making the problem difficult to avoid.

    Photo: Steve Mace

  • Storm Slabs

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

    Natural and human-triggered storm slab activity was widespread as snowfall rates and temperatures increased throughout the day on Sunday. This morning, upsidedown and wind-stiffened slabs will still be sensitive, even on sheltered slopes. This includes road cuts, gully features, cliff bands, and mid-slope depressions. Significant snow has accumulated in mountain communities. Be aware of overhead hazards from roofs and short steep slopes above confined areas.

Avalanche Discussion

Natural and human-triggered avalanches were common over the past 24 hours. Snowfall rates increased into the evening before tapering. At the same time, winds increased and will remain strong through midday.

Most of the avalanche activity reported yesterday failed within the new snow. Avalanches between 1/31 and 2/3 broke on a melt-freeze crust or surface facets buried on the last day of January. On slopes that held snow in December, avalanche activity over the past week has occurred on a layer of depth hoar buried between 3 and 7 feet below the snow surface under a strong mid-pack slab. Lower than average snow depth had previously contained impacts from avalanches involving these layers to upper elevations. Plenty of new snow has accumulated in the tracks and runouts of northerly avalanche paths. So, avalanches releasing above treeline now threaten the runouts and flat terrain below.

Snow removal equipment and emergency services will be working to catch up to the impacts the storm has already caused to towns and highways. Park responsibly to allow access to these critical services. Travel in avalanche terrain is not recommended.

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