Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Since yesterday morning, sustained winds with strong gusts have transported snow forming new wind slabs and adding weight to buried weak layers. Dangerous avalanche conditions exist at the mid and upper elevations, where skiers and riders could easily trigger small to large slab avalanches in steep avalanche terrain. The initiation of a newly formed surface slab could result in the failure of deeper weak layers in the snowpack and trigger a large to very large avalanche that could run long distances. At the lower elevations, slab avalanches are expected to be smaller and isolated to steep avalanche terrain. At all elevations, backcountry travelers should carefully assess terrain for recent wind loading as these slopes will be the most sensitive to triggers.

Avalanche problems

  • Wind Slabs

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

    For over 24 hours, southwesterly winds have averaged 30 to 40 miles per hour with gusts in the 50s. Strong winds have redistributed loose snow onto the leeward sides of terrain features and have formed slabs one to three feet in depth on a variety of aspects. Although wind slabs could be found on many slopes today, easterly-facing slopes at the mid and upper elevations will have the most significant loading and slab formation, and backcountry travelers should definitely avoid these starting zones. At the lower elevations, gusty winds have affected the snow’s surface but slab avalanches will most likely fail on buried persistent weak layers.

  • Persistent Slabs

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

    The depth of persistent weak layers that are buried within the snowpack depends on the elevation. These slabs will be hard to detect and previous tracks on a slope are not an indication of stability. At the mid and upper elevations, these weak layers will take a significant load, like a wind slab, to trigger a large to very large avalanche with depths of four to six feet. At the lower elevations and in areas with a thin snowpack, a one to three-foot slab could be triggered by the weight of a single person. Although less likely to trigger a persistent slab avalanche, the outcome would probably have severe or deadly consequences.

Avalanche Discussion

As pacific moisture moves into the region, light snowfall is expected to develop overnight and into tomorrow with limited accumulation. For tomorrow afternoon, the National Weather Service is issuing a Winter Weather Advisory, and significant snowfall is expected to last through Saturday. Mountain temperatures should drop into the low-teens and then tomorrow rise into the upper-teens. Westerly ridgetop winds are expected to be twenty to thirty miles per hour with higher gusts. In the Togwotee Pass and Grey’s River forecast areas, the avalanche hazard is expected to be Considerable above 7,500 feet. Backcountry travelers could trigger slab avalanches one to five feet in depth on steep avalanche terrain. Smaller surface slabs, which could be more easily triggered, have the potential to step down into deeper weak layers, resulting in large to very large avalanches. Below 7,500 feet, slab avalanches will be one to three feet and limited to steep avalanche terrain. In the Teton forecast area, the avalanche hazard is expected to be Moderate. It will be possible for riders and skiers to trigger wind slabs one to two feet in depth at the mid and upper elevations. In some isolated areas, the potential remains for surface slabs to step down to deeper weak layers. At the lower elevations and where the snowpack is thin, persistent weak layers could be triggered by the weight of a single person. Backcountry travelers should monitor tomorrow’s storm as conditions could quickly change and increase the hazard when heavy snowfall and strong winds move into the area.

Regions covered