Bulletin d’avalanche

Tetons

Bridger-Teton Avalanche Center
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Danger d’avalanche

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

Points saillants

While unlikely, the chance exists for backcountry travelers to trigger a large avalanche that fails on weak snow in the lower half of the snowpack. Shaded terrain at the middle and upper elevations that is steep, rocky, and unsupported could produce a destructive avalanche. In addition, be on the lookout for small pockets of wind-drifted snow in exposed terrain at the highest elevations.

Problèmes avalancheux

  • Persistent Slabs

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

    Slabs of cohesive snow 1-3 feet thick overlay weak, faceted snow that formed during a dry period in November. While unlikely, the potential exists to trigger an avalanche at this interface on northwest through northeast aspects above 8,500’. Collapsing the weak layer in a shallow portion of the snowpack, especially in very steep and unsupported terrain, is the best way to trigger one of these avalanches. Keep in mind that a slope can be ridden several times before a particularly thin, weak spot is impacted. 

    Maintaining a reasonable margin around steep rocky terrain or hanging snowfields above cliffs is still a prudent decision. Furthermore, digging a quick snow pit can help verify the existence and severity of weak snow in terrain that you wish to ride. Before entering steep consequential terrain, take a minute to think about the structure beneath your feet and the consequences of being caught in an avalanche.

    Yesterday’s 2-4” of snow combined with moderate winds out the west have created very shallow soft slabs (3-8”) on leeward aspects above 10,000’. These slabs are mostly harmless to humans except in extreme terrain where being knocked off one's feet could carry severe consequences.

    An old avalanche from 12/8 on the east face of Taylor Mountain.

    This is a great example of "steep, unsupported terrain".

Avalanche Discussion

Currently, the snowpack in the Tetons is mostly stable with the exception of very steep unsupported terrain that faces north. Nearly two weeks without a significant loading event has given the weak snow in the lower half of the snowpack time to adjust to the load from the early December storms. Consequently, it has become difficult, but not impossible, to impact the weak layers at the base of the snowpack. Stability test scores from the past week have shown a mix of propagating and non propagating results. While this trend is encouraging, propagation observed in pits dug yesterday shows that the potential to trigger an avalanche still exists in high elevation north facing terrain.

Although we are trending towards low avalanche hazard, it is important to practice safe backcountry travel habits. This means exposing only one person to avalanche terrain at a time and stopping in appropriate safe zones. Don’t be fooled into thinking that the current persistent slab problem involving the November drought layer will fade away quietly. The next significant loading event will likely bring it back to the forefront of our concerns.

Régions couvertes