Avalanche forecast

Tetons

Bridger-Teton Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

The avalanche danger today is Moderate. Heightened avalanche conditions exist in steep terrain where a persistent layer of weak snow exists. It is possible for the weight of a skier or rider to trigger a deep slab avalanche, generally on high, shady slopes. While triggering this type of avalanche is trending towards unlikely, the consequences of doing so would be dire. Evaluate terrain carefully and dig on representative slopes to identify the presence of this weak layer before committing to consequential terrain. Tracks on a slope do not mean that the slope is free of this weak layer. At lower elevations, recent warm temperatures, wet snow and rain created a crust that has stabilized the snow.

Avalanche problems

  • Deep Persistent Slabs

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

    Slab depths over the December 5th interface of weak faceted snow and crusts vary from 3 to 8 feet depending on aspect and elevation. A hard slab has formed in many locations over this layer. The most recent avalanche activity on this layer is a reminder that it may remain reactive to human triggers. When dealing with persistent weak layers that are buried several feet deep, warning signs such as cracking and collapsing will probably NOT be encountered and previous tracks do NOT indicate stability.

  • Wind Slabs

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

    Snow and wind during the most recent storm formed wind slabs at the mid and upper elevations. These wind slabs have most likely settled and bonded in most places but they have added load to buried weak layers. While these will likely be stubborn to trigger, an avalanches could be 1 to 3 feet in depth. Winds slabs will be more easily triggered on very steep, unsupported slopes, especially if slopes warm during periods of direct sunlight.

Avalanche Discussion

Slightly warmer temperatures under sunny skies are on tap for tomorrow as high pressure remains in place. Expect high temperatures in the thirties tomorrow afternoon with a light westerly wind in the mountains. Solar gain on sunny aspects is unlikely to contribute to anything other than some surface instabilities. The main problem tomorrow will be the lingering risk of triggering a very large avalanche on the buried, weak snow which leads us to a Moderate danger rating. The potential remains for a skier or rider to trigger the weak layer over a thin spot in the slab. In some steep and previously wind loaded areas, the resulting slab could be well over five feet thick and unsurvivable. Keeping to lower angled slopes at middle and upper elevations is the best way to avoid this problem. Stepping into steep, wind-loaded, or unsupported terrain with consequences may be the best way to find this problem.

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