Bulletin d’avalanche

Tetons

Bridger-Teton Avalanche Center
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Danger d’avalanche

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

Points saillants

Recent snow and wind have formed soft slabs up to 18” deep at the upper elevations. These slabs will be most sensitive in wind affected, upper elevation terrain. In addition, it remains possible for riders to trigger deeper avalanches that fail on weak snow in the middle of the snowpack. Watch out for areas where the new snow is drifted and carefully evaluate deeper weak layers in the snowpack if venturing into steep terrain. 

The west side of the Tetons was favored by recent snowfall. Avalanche conditions will be most dangerous on the west side.

Problèmes avalancheux

  • Wind Slabs

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

    Ridgetop winds averaging 20 mph out of the west along with 5-10” of new snow in the past 24 hours have formed soft slabs 6-18” deep on exposed leeward aspects at the upper elevations. Watch out for signs of wind loading such as “upside down” feeling snow, cracking, or smooth pillow features. Snowfall favored the west side of the Tetons. Expect soft slabs to be deeper and more sensitive on the west side.

    Sensitive soft slabs reported on the west side of the Tetons (2/3).

  • Persistent Slabs

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

    While trending less likely, it is possible for skiers and riders to trigger large hard slab avalanches failing on weak snow that persists in the middle of the snowpack. These slabs are 2-4 feet deep above 7,500’. Shaded aspects were least impacted by the recent warm weather. As a result, they are the areas where it will be easiest to find the persistent slab problem. Triggering one of these avalanches is most likely in locations where the slab is at its thinnest, making it possible for humans to impact the weak layer. Examples of terrain where thin spots exist include very steep, convex, rocky, and wind affected terrain features. Avalanches involving new snow could step down to deeper layers in steep and sustained terrain. This avalanche was remotely triggered yesterday south of Teton Pass and shows  that humans can still impact the January 4th weak layer in certain terrain.

    There will be a noticeable hardness change (hard to soft) in the middle of the snowpack at the January 4th interface. Digging and probing for depths to this interface can provide you with an idea of how thick the slab is in the terrain you wish to ride. If you are consistently finding thin spots in the slab, or are uncertain about the terrain around you, then defaulting to simpler terrain remains a good call.

    A persistent slab avalanche that was remotely triggered yesterday (2/3) south of Teton Pass. Crown visible through trees

Avalanche Discussion

The two avalanche problems that you may encounter today have distinctly different characteristics. Soft slabs that have formed from the recent snow and wind can be easily found in steep, windy, upper elevation terrain. The likelihood of triggering one of these slabs is fairly high where they exist, however, they are also easy to predict. Cracking and obvious signs of instability will be present. At the moment, these slabs could be triggered from a distance, but are most likely to release under your skis or sled when you impact the slope. 

The persistent slab problem is uniquely different. The chances of triggering one of these avalanches has decreased significantly, yet they are still possible and will present little warning before they release. This makes them much more difficult to predict and potentially more dangerous given the size and potential for propagation. Regardless of the type, getting caught in any avalanche can have severe consequences. Because of this, it is important to practice safe travel habits and carefully evaluate conditions in windy, high elevation terrain today, all the while being aware of the weak structure that lurks deeper in the snowpack.

Régions couvertes