Bollettino valanghe

Tetons

Bridger-Teton Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

It is possible to trigger an avalanche 1 to 2 feet deep in steep (>30°) wind-loaded terrain at upper elevations. Although less likely, these slabs could act as a trigger, causing a larger more destructive avalanche on weak layers buried 2-4 feet deep. Carefully evaluate wind-affected, steep, and rocky slopes where avalanches are most probable. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Isolated pockets of wind slabs 1 to 2 feet thick remain a threat in exposed terrain at upper elevations. These slabs often form along ridgelines and around exposed complex terrain features such as gullies and rocky outcroppings. Look for signs of wind-affected snow such as pillows, drifts, or stiffened surfaces. Use caution if you encounter obvious signs of instability such as shooting cracks. These avalanches could trigger buried weak layers, causing a larger more destructive avalanche. Riding on sheltered slopes will help manage this problem. 

    (1/6/2025)

    A snowboarder triggered an avalanche in very steep terrain, SE 9800 feet on Jan 6. 

    Photo: Bridger-Teton Avalanche Center

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    Weak layers of snow that were buried in mid-December are becoming more unreactive. Triggering a large avalanche at depths between 2-4 feet is unlikely but not impossible. This avalanche problem is currently a low likelihood/high consequence scenario. If venturing into bigger, steeper terrain, remember that these layers lurk deeper in the snowpack.  It will probably take a larger trigger, such as a smaller avalanche or large cornice, to impact these deep layers. Yesterday, a large avalanche, likely triggered by a wind slab, was reported in Saint Patty's Day Couloir. Very steep (>35°), rocky, and unsupported terrain features should still be approached cautiously. Pick terrain that reduces your exposure to overhead hazards in the event your assessment of deeper weak layers is wrong.  Using safe travel protocols will help to minimize your chances of triggering an avalanche. Travel one at a time, use islands of safety when stopping, and watch out for terrain traps.

     

    A wind slab avalanche that likely stepped down into old snow. 

    (1/9/2025) St. Patty's Day Couloir SS-R3-D2.5-N-O. 

    Photo: Brian Smith

Avalanche Discussion

Yesterday, a large avalanche failing on deeper weak layers was reported in the Saint Patty's Day Couloir. This avalanche was likely triggered by a smaller wind slab that released from the ridgeline above. This avalanche serves as an important reminder that persistent weak layers may still be triggered. These layers are trending towards unreactive, but yesterday's event proves that larger triggers can still cause an avalanche. Check the observation photos and note how that terrain contains multiple features that should raise alarm. There is a steep wind-affected ridgeline, rocky outcroppings, and old snow due to the NE aspect. Approach terrain similar to this with caution. The best way to manage the uncertainty surrounding this problem is to stick to sheltered slopes and lower-angle terrain. 

Please continue to send your observations to us. Thanks!

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