Lawinenlagebericht

Snake River Range

Bridger-Teton Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 2 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

New snow and wind have made triggering a soft slab avalanche up to 18 inches deep likely in steep, wind loaded terrain at the upper elevations. Triggering a deeper avalanche that fails on weak layers buried 2-4 feet deep remains possible. Very steep, rocky, and wind affected terrain should be avoided given the higher likelihood of triggering a large avalanche in those locations. Be prepared to move to low angle terrain if you observe instability in the new snow such as cracking. Careful snowpack evaluation and conservative decision making are recommended around avalanche terrain today.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Nearly 10 inches of new snow fell yesterday in the Snake. Moderate winds out of the west/northwest have redistributed this snow and formed soft slabs up to 18 inches deep in wind-loaded terrain at the upper elevations that are likely to be sensitive to the weight of a rider. Multiple skier triggered soft slabs were reported yesterday afternoon in the Tetons. Expect similar activity today. Be on the lookout for signs of wind loading including blowing snow and drifts. Cracking indicates unstable snow. Move to sheltered, low angle terrain if these conditions are observed.

    Cracking in the new snow indicates instability.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    Weak layers of snow are buried 2-4 feet deep in most mid and upper elevation locations. The likelihood of triggering an avalanche involving these weak layers is slowly decreasing, yet remains possible today in steep terrain. Slopes on the north half of the compass are most suspect. The last human triggered avalanche involving these layers was reported on December 30th. Use extra caution around rocky, wind affected, and unsupported slopes as they are the places where a human is most likely to impact the weak layers buried below. Tracks on a slope do not indicate stability with this problem.

    It is important to increase your margin of safety given the uncertainty and high consequences associated with triggering a persistent slab avalanche. Traveling one at a time, stopping in islands of safety, and avoiding steep gullies or cliffs are all ways to increase your margins while traveling around avalanche terrain. However, riding terrain that is under 30° with no significant overhead hazard remains the best way to avoid this problem.

    A large remotely triggered avalanche that failed on persistent weak layers in the Snake River Range.  Two riders were caught in this slide.

    (12/31/2024)

Avalanche Discussion

A significant pulse of snow yesterday has kept new snow instabilities on the radar for another day. Be on the lookout for signs of instability and use caution around wind-loaded start zones in the upper elevations. 

The Snake Rivers are on the tail end of a slow, but steady loading cycle. Measurable snowfall has been recorded nearly every day since December 23rd. Cohesive slabs of snow 3.5-4 feet thick lie above weak snow that developed earlier in the winter. In many places, the weight of a rider is unlikely to impact the weak snow buried near the ground. Yet, it is important to remember that the snowpack is still under stress. Ten day cumulative snow water equivalent (SWE) values are just now peaking around 5 inches. This is a significant amount of weight and adjustment to loading takes time. Cornice and explosive triggered avalanches failing on deeply buried facets are reminders of what lurks below. Instabilities in the middle of the snowpack that developed around the Christmas storm have been largely unreactive over the past week despite snow pit tests showing mixed results. The snowpack will continue to adjust over the next week of relatively quiet weather and instability will trend downward. For the time being, it is important to maintain safe travel habits and approach steep terrain with a healthy dose of skepticism.

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