Bollettino valanghe

Banner Summit

Sawtooth Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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In sintesi

You can trigger very large, 2-3 foot thick slab avalanches that fail on widespread layers of weak snow. Avalanches can be triggered from long distances away from steeper slopes. Smaller avalanches involving only the recent snowfall are also possible. These natural and triggered slides may break into the weak layers beneath, creating much larger, more destructive avalanches. 

Problemi valanghivi

  • Persistent Slabs

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

    Triggering a very large avalanche is a worrisome possibility. Some of these slides will be powerful enough to destroy a house. The primary weak layer of facets and/or surface hoar on shadier aspects and crust + facet combinations on sunnier slopes are fragile and can be found on most slopes.

    Weak layers are beginning to gain strength, and the odds you trigger a Persistent Slab are decreasing, but ongoing snowfall will slow the process.These avalanches can break in surprising ways. Don't expect obvious signs of instability, like cracking or collapsing before triggering a slide. You can trigger them from flat or low-angle terrain long distances away from steep slopes. The only way to manage this problem is to avoid avalanche terrain, including the base of slopes that are threatened from above. 

    (1/22/2024) The debris of this slide ran into a creek, a lower and mid-elevation terrain trap that is characteristic of the Banner Summit Zone. Terrain features like these multiply the consequences of these slides.

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Expect pockets of wind slab to be reactive to your body weight and larger as you climb higher in elevation. As wind and snowfall continue throughout the day, expect the size and reactivity of these slabs to increase. 

    Importantly, these smaller slides can trigger much larger, much more dangerous avalanches on the persistent weak layer described above. Keep an eye out for rippled surfaces, hollow-sounding stiff snow, and cracking shooting out from your skis. The low-density snowfall will mask the presence of these slabs. Avoid drifts, dunes, and pillows.

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