Bulletin d’avalanche

Togwotee Pass

Bridger-Teton Avalanche Center
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Danger d’avalanche

Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
Sans niveau
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Large, dangerous avalanches remain possible on persistent weak layers near the ground buried 2-4 feet deep. Although less likely, these avalanches could be triggered remotely from gentle terrain above, below, or to the side of steep slopes. This problem is widespread, but use heightened caution on complex terrain with wind loaded slopes where the consequences will be more severe. Seek simple terrain to manage the uncertainty of this problem.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–2.5

    The possibility of triggering a large avalanche will continue as weak layers persist near the ground. These weak layers are buried below hard slabs 2 feet across all elevations and up to 3-4 feet in wind-loaded upper elevation terrain where the consequences remain more severe. On Jan 4th a fatality occurred on Radio Tower Peak by triggering a persistent slab avalanche. 

    Obvious signs of instability may not be present, as slopes can behave in unpredictable patterns. Avalanches could be triggered remotely from gentle terrain above, below, or beside steep slopes. These avalanches can also occur after multiple tracks have hit a slope. Given the well-connected nature of the weak layer, avalanches can propagate long distances across slopes. Evaluate terrain carefully and steer clear of rocky, unsupported slopes over 35° steep in wind affected terrain. Watch for areas that have been recently wind loaded and will be more sensitive to human triggers. Triggering a small wind slab will likely step down to deeper weak layers. Avoid terrain traps where even small avalanches can be dangerous. 

    (1/5/2025)

    Looking up from the burial site at the remotely-triggered large avalanche off the west shoulder of Brooks Lake Mountain near Breccia. 

    Photo: Bridger-Teton Avalanche Center

Avalanche Discussion

Identifying Terrain

The Avalanche Terrain Exposure Scale (ATES) classifies terrain into five categories based on the 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 to start riding more complex terrain. 

Complex: Exposure to multiple overlapping avalanche paths or large expanses of steep, open terrain. Sustained exposure to overhead hazard. 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 hazard. 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. 

 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!

Régions couvertes