Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Thu
Alpine
4 · High
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Out of date — this forecast expired 3 years ago.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

You can trigger very large, 2-4 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. 

Conditions are at their worst in this zone's southern and western portions, including the mountains above Smiley Creek.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    You're likely to trigger a large, unsurvivable avalanche. Some of these slides will be powerful enough to destroy a house.  A week of heavy snowfall is stressing weak layers near the base of the snowpack. These layers 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.We have limited recent observations from the majority of this zone, but multiple Persistent Slab avalanches were triggered in neighboring zones over the past week. These avalanches can release in surprising ways. 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. 

    This large remotely-triggered persistent slab avalanche on a NE slope at 9400' above the East Fork of the Big Wood broke 250ft wide and ran over 1000' downslope.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    This zone picked up an additional 3-15" of snow in the last 24 hours, heavily favoring the S. Fork of the Boise and the mountains above Smiley Creek. This rounds out a week of storms that brought anywhere from 1-3' of snow. Expect to find thick, touchy, slabs in areas that were affected by recent SE wind. These dunes, drifts, and pillows will be masked by ongoing snowfall and may be hard to identify.  While less likely, slab avalanches are also possible on steep slopes that are sheltered from the wind. Cracks shooting out from under your feet indicate you have found a sensitive slab.

    Loose snow avalanches are a real concern. These will be easy to trigger and may release naturally if the sun pops out this afternoon. Importantly, any of these smaller slides can trigger the much larger, much more dangerous Persistent Slab Avalanches described above.

Regions covered