Bulletin d’avalanche

Togwotee Pass

Bridger-Teton Avalanche Center
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Danger d’avalanche

Thu
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

Triggering a large avalanche that fails on weak snow buried 2-3+ feet deep remains possible in steep, wind-affected terrain. Avalanches in these locations can also be triggered from below. Evaluate steep slopes over 30 degrees for signs of wind loading or stripping.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Weak snow that formed in early December sits 1-3 feet below the surface and remains a lingering threat today. While triggering these deeper layers is becoming less likely as time passes, it cannot be ruled out considering the extent of weak snow in the zone.  The last reported human-triggered avalanche involving these weak layers occurred a little over one week ago. Thin spots in the slab are the most likely places to impact these layers. Thin spots usually exist around very steep, rocky, and wind-blown terrain features.

    Significant triggers in the form of groups, snowmobiles, and falling cornices will increase the odds of impacting these layers. Use safe travel practices to minimize your exposure to this problem. Travel one at a time across steep terrain, avoid steep gullies, and communicate plans with your group members throughout the day.

    Additional Discussion: Recent snowfall appears to be bonding well to old surfaces. No new avalanches were reported yesterday, and winds have remained light. Wind slabs were removed from the problem list today, although it remains a good idea to check for unstable wind drifts if traveling to the highest reaches of the forecast zone.

    (1/13/2025)

    This photos shows an example of where you can trigger persistent weak layers. 

Avalanche Discussion

The knowns:

  • Recent snowfall is being compacted into harder slabs of snow at upper elevations, whereas riding in protected meadows and rolling, low-angle hills remains preserved (and fun).
  • Numerous large avalanches were reported here last week.

The unknowns:

  • How well is the new snow bonding to the old snow surfaces?
  • Will additional observations of avalanche activity show more slides that broke deeper in the snowpack or reveal new surface snow instability patterns to watch out for?
  • Where is weaker snow near the base of the snowpack still a concern? Where is it less of a concern?

Safe travel practices remain important, including good communication, traveling one at a time in avalanche terrain, and checking out the snow before committing to steeper slopes on different aspects. The differences in snowpack here range greatly between the east and west sides of the range, as well as north vs south. Being clued into the snowpack history where you ride can help inform your riding plan for the day and avoid the two problems listed above. In many locations, the snowpack is trending towards more stability. Where the two problems overlap is also where it is most likely to trigger a larger avalanche.  Rocky, unsupported, or wind-stripped, shallow slopes that still hold snow should be avoided. Until the list of "knowns" is longer than the "unknowns," keep tight margins on the terrain you choose to enter, not only about slope steepness but also the shape of that terrain and the depth/structure of snow on its slopes.  

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