Bulletin d’avalanche

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Danger d’avalanche

Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Dangerous avalanche conditions exist today. Human-triggered avalanches are likely in steep terrain. Avalanches can be triggered in areas where the wind has built drifts and in areas sheltered from the wind, as well as while approaching or riding a slope, from adjacent terrain, or below.  

Expect avalanche danger to increase significantly as as heavy snowfall and wind arrive early this evening. 

 

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–3

    Large, deadly avalanches failing on very weak snow formed in December continue to be threat today. Avalanches could break 3-5' deep in some areas in the middle and upper elevations though 1-3' slabs are most likely. Below 7,500’, slab depths will also be in the 1-3' range. Slabs could be triggered from a distance or wait until you ride the slope to release. While there was no observed natural avalanche activity yesterday, the new snow falling today will keep the buried weak layer near the failure point. 

    Keep a good distance from terrain connected to avalanche paths and ride slopes well below 30°. Being aware of the terrain above you will be challenging today due to limited visibility. Groomed trails that cross avalanche paths should be evaluated carefully and crossed one at a time.

     

    (1/16/2024)

    Many avalanches like this occured during the last avalanche cycle. The weak layer responsible will receive another heavy load in the next 36 hours.

    Photo: Gabrielle Antonioli

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3.5

    Weak snow formed during a dry period in November persists at the base of the snowpack. This layer is now buried about 5 to 6 feet deep in the Salt River, Snake River, and western portions of the Wyoming Range. It is at its weakest on the north half of the compass. The recent loading events have pushed this deep weak layer to its breaking point in some locations. Deep slab events were observed in the Snake River Canyon two days ago. These very large avalanches are most likely to occur when an avalanche triggered in the most recent snow steps down to weak old snow. Any avalanche involving the entire snowpack will be destructive and likely unsurvivable. 

    Areas in the eastern Wyoming Range, Hoback Canyon, and Gros Ventre Mountains lacked significant snowfall prior to the storm cycle beginning January 4th. In these locations, the new snow has fallen on a snowpack that was primarily made up of weak, sugary snow. Deep slab events are not likely in these locations due to the shallower snowpack.

    (1/16/2024)

    This avalanche failed much larger than it did a few weeks ago. The crown depth indicates that it involved the deeper weak layers from November. 

    Photo: Gabrielle Antonioli

Avalanche Discussion

Riding along the Smith Fork river road yesterday during perfect visibility was humbling. We observed about 20 large avalanches on the east facing slopes of the front range in the course of just a few miles of trail riding. These avalanches mostly involved the 24-32" of snow thats fallen in the past week or so with crown depths around two feet thick. Most of the avalanches propagated a long distance and all of them could easily bury a person which took crown profiles off the list of tasks to complete for the day. Visual observations painted a pretty clear picture though. It was clear that many slopes had failed and reloaded during the prolonged stormy period over the weekend, testament to the sensitivity of the buried facets/surface combintion present on the surface buried starting January 4.

Temperatures remained cold yesterday and limited the solar effect that led to some very large natural avalanches the day prior. Snow depths indicate that all the recent snow has settled into a cohesive slab, now a thick slab sitting on what has proven to be an historically weak layer. Snow arriving during this next Pacific system seems likely to produce even larger avalanches than the last cycle, particularly considering the wind loading that will occur. For today, the new snow on the slightly more stubborn slab will keep the snowpack on the edge of failure. Overnight and tomorrow will likely be another tipping point. 

Please submit observations of avalanches to help us track conditions in the area! Observations can be simple or elaborate, with or without photos, and with or without your name. Thanks to everyone who has submitted this season...you are making a difference!

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