Avalanche forecast

Banner Summit

Sawtooth Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Triggering a very large, 2-3 foot thick slab avalanche is a worrisome possibility. These slides 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. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    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.

    The odds you trigger a Persistent Slab are decreasing, but the consequences remain severe. 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. ADDITIONAL DISCUSSION:This zone picked up about a foot of snow in the last week. Look for small wind slabs at upper elevations. Loose snow avalanches (sluffs) are likely in steep terrain. These small slides may run fast and far on stout crusts and have the potential to trigger the Persistent Slab problem described 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.

Regions covered