Bollettino valanghe

Snake River Range

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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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

It is possible to trigger a large avalanche on weak layers buried 2-4 feet deep. Smaller wind slab avalanches are possible and could act as a trigger for larger avalanches. Carefully evaluate wind-affected, steep, and rocky slopes at upper elevations. Avalanches are unlikely at lower elevations. 

Problemi valanghivi

  • Persistent Slabs

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

    Weak layers of snow formed in December remain buried 2-4 feet at the base of the snowpack. It is possible to trigger a large avalanche on steep slopes at middle and upper elevations primarily on northern aspects. Triggering an avalanche is most likely in thin areas around rocks or in exposed terrain where the wind has drifted snow. The likelihood of this problem is trending down, but the consequence remains very high.Yesterday, a large avalanche, likely triggered by a wind slab, was reported in the neighboring Teton zone. The problem is worse on shady aspects, but with a big enough trigger, any steep slope with weak, sugary snow at the ground remains suspect. Obvious signs of instability such as shooting cracks are usually absent with large hard slab avalanches.  Give yourself plenty of room around steep slopes, and remember that you could trigger a steep slope just by riding underneath it.

    (1/7/2025)

    Large persistent slab avalanche within the last 72 hours on a steep, rocky, north-facing slope.

  • Wind Slabs

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

    Recent snow and wind have formed slabs up to 1 foot thick at upper elevations. Slabs up to 2 feet thick may be found on isolated terrain features. 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. 

    (1/9/2025)

    Natural avalanche at 9200' E aspect on wind-loaded upper elevation terrain from the neighboring Salt and Wyoming Ranges zone.

    Photo: Bridger-Teton Avalanche Center

Avalanche Discussion

Identifying Terrain

The Avalanche Terrain Exposure Scale (ATES) classifies terrain into five categories based on avalanche characteristics: Non-avalanche, Simple, Challenging, Complex, and Extreme. As we highlight in avalanche courses, the best way we can manage avalanche problems is to choose the type of terrain we enter. Right now we have a persistent slab problem across the forecast area. Over time without additional stress of snow or wind, these buried weak layers become harder to trigger. The main reason for this is the overlying slab is generally getting deeper and harder, so impacting those weak layers is difficult. Now the problem is that there are thin, sensitive areas where you could trigger a large to very large avalanche. The terrain you are most likely to find that trigger point is in complex or extreme terrain. These categories of terrain are generally exposed to a lot more wind causing variable snow depths, and hold much more avalanche-prone terrain (steeper). You can simplify managing our current persistent slab problem by staying out of complex or extreme terrain. The more you enter those categories of terrain, the higher your odds are of finding that thin, trigger point. Do you want to lower your odds or increase your odds of triggering a large avalanche? Stack the odds in your favor and choose your terrain wisely. Identify terrain based on slope angle and communicate where you are going with your partners. Avalanche conditions will eventually improve, so it’s best to be patient and wait until the right conditions start riding more complex terrain. 

Complex: Exposure to multiple overlapping avalanche paths or large expanses of steep, open terrain. Sustained exposure to overhead hazards. Many avalanche starting zones and terrain traps with minimal options to reduce exposure.

Extreme: Exposure to very steep faces with cliffs, spines, couloirs, crevasses, or sustained overhead hazards. No options to reduce exposure and even small avalanches can be fatal.

Our sincerest condolences go out to everyone in the community influenced by the recent avalanche fatality this week. A detailed observation of the incident can be viewed here: Radio Tower Peak.

 Please consider submitting an observation HERE. Observations allow everyone to gain a better and more complete understanding of conditions. Thank you to everyone who has submitted observations this season!

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