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

In sintesi

Dangerous avalanche conditions exist throughout the forecast area.  Expect the likelihood of large avalanche activity to rise throughout the day. Travel on, near, or underneath avalanche terrain is not recommended.

Problemi valanghivi

  • Wind Slabs

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

    Heavy snowfall and strong to extreme SW winds have created dangerous wind slab conditions on northerly and easterly terrain features near and above treeline. Expect the size and distribution of fresh, sensitive wind slabs to grow substantially today as strong winds and heavy snow continue to impact the forecast area. Be suspect of terrain features that encourage drifting such as the leeward sides of ridgelines, gully features, and cross-loaded depressions.  Large natural and human-triggered avalanches are likely today. Keep in mind that even a relatively small wind slab avalanche breaking in the upper snowpack has the potential to "step down" to weak layers near the ground, creating a much larger and more destructive avalanche.   Be aware of what is above you today; traveling in and below avalanche terrain is not recommended.

    (1/24/2024)

    A remotely triggered hard wind slab avalanche broke in the recent storm snow and ran on an older wind slab. The crown started 6 inches deep and reached 2 feet deep across the slope. D1.5: about 80 ft wide and ran about 100 vertical feet. Did not step down to buried persistent weak layers.

    Photo: Eastern Sierra Avalanche Center

  • Persistent Slabs

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

    This current storm system is adding significant stress to a weak snowpack. By the end of the day today, up to 2 ft of new snow and almost 2” of water weight could be added to the equation, increasing the likelihood of both natural and human-triggered avalanches. This is particularly true near and above treeline, where basal facets remain dry and well-formed following our latest warm-up. If triggered, a resulting avalanche could break with little warning, involving the full depth of the snowpack. It will be possible to trigger a persistent slab avalanche from adjacent slopes today. Avalanches may propagate long distances and beyond terrain features typically containing surface instabilities such as storm or wind slabs.  Travel in and below avalanche terrain is not recommended.

    (1/25/2024)

    Bloody Couloir: not what you want to see on your local 50 classic.

    Photo: Everett Phillips

  • Storm Slabs

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

    Up to 13” of new snow has been recorded at the time of publishing. Over a foot of additional snow is possible along the Sierra crest today, with snowfall rates over 1” per hour this morning. Storm instabilities, both slabs and sluffs, will grow in size and become more sensitive as the day progresses. Avoid being on or under terrain over 30° today, and be mindful of your exposure to terrain features that increase the consequences of avalanches. This includes road cuts, gully features, cliff bands, and mid-slope depressions. Be wary of overhead hazards today and avoid being in or underneath avalanche terrain.

Avalanche Discussion

Extreme caution is advised if you decide to head into the backcountry today.  Large and destructive avalanches will become more likely as the day progresses.  

Top of mind for the forecast team is the weak, faceted base of our snowpack. Today's storm has added a heavy load and a lot of stress to the equation. Keep in mind that even a relatively small avalanche breaking near the surface has the potential to step down to the ground creating a much larger and more destructive avalanche.  Warm temperatures over the last week have added strength to basal facet layers at lower elevations. Still, recent observations have confirmed no major change to this weak layer near and above treeline. It is critical to remember that an avalanche breaking near the ground today has the potential to run long distances and into lower-elevation terrain.  Give yourself wide terrain margins, and avoid being on or underneath steep slopes.

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