Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

Large slab avalanches capable of killing or severely injuring a person were triggered by humans in the Wyoming Range yesterday and on Wednesday. Similar events are possible in the Teton area today. These dangerous slabs are failing on a persistent weak layer (PWL) and could be triggered by the first person who crosses a slope or after a slope has been crossed multiple times. Audible whumps and collapses on this PWL continue to occur on a variety of aspects and are indication of instability. Assess terrain carefully and make conservative choices.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    At the mid and upper elevations large slab avalanches up to three feet in depth can be triggered by the weight of a single person on a variety of aspects. Temperatures at elevation are up to 15 degrees warmer than they were yesterday morning. Warming temperatures may increase snow creep on steep slopes as the snowpack adjusts to the load placed on it by the recent extended storm cycle. As the day warms that creep may increase stress on the PWL and increase the sensitivity of these slabs to human triggers. At the lower elevations any slab avalanches are expected to be less than a foot deep and limited to isolated terrain features.

Avalanche Discussion

The high-pressure ridge will move eastward ahead of a cold front that is expected to impact the forecast area by Saturday morning. Snow should develop first over the Tetons and Togwotee Pass and then quickly spread south to the Southwest Trails. Accumulation is expected to be 4 to 10 inches across the region by Sunday morning. Temperatures will start in the teens with a slight valley inversion and then warm into the twenties. Ridgetop winds are expected to be southwesterly at 10 to 20 miles per hour with stronger gusts. On steep slopes, dangerous avalanche conditions remain a concern, where the weight of a single person could trigger a one to three foot deep avalanche. Above 7,500 feet, the general avalanche hazard is expected to be Considerable in the Southwest Trails and Teton areas and Moderate on Togwotee Pass. Below 7,500 feet, where avalanches are unlikely, the general avalanche hazard is Low. As tomorrow’s new snow loads slopes, the increased weight could add to the potential of triggering persistent slabs. These killer slabs could be triggered by the first person or after a slope has been crossed many times. Careful assessment of terrain is important for safe travel in the mountains.

Regions covered