Bulletin d’avalanche

Tetons

Bridger-Teton Avalanche Center
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Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 8 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Triggering a large avalanche that fails on weak layers of snow buried 2-3 feet deep is possible in very steep terrain today. Wind loaded slopes at the upper elevations are most dangerous. Signs of instability, such as cracking or collapsing, may not present themselves prior to triggering. Conservative terrain choices and thorough snowpack evaluation are recommended today.

Problèmes avalancheux

  • Persistent Slabs

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

    Weak layers of faceted snow that formed in November sit below recently formed slabs and are under considerable stress from recent loading. These slabs are generally 2-3 feet thick and could be hard or soft depending on location. This problem is confined to upper elevation terrain and shaded aspects at the mid elevations. East through north facing slopes held the most continuous and well developed weak snow prior to the recent storms. While the likelihood of triggering is slowly decreasing, there is still a good chance that a human can trigger a large persistent slab avalanche in very steep (>35deg) upper elevation terrain. Wind loaded slopes will produce the largest and most destructive avalanches. It is likely that obvious signs of instability, such as cracking or collapsing, will not be present prior to triggering.

    A large explosive triggered hard slab at JHMR. This avalanche is about 3 feet deep and failed on faceted grains above a melt freeze crust -(12/8/2025)

  • Wind Slabs

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

    The Tetons have picked up 6-8 inches of very dense snow in the past 48 hours. Strong and sustained winds out of the southwest accompanied snowfall forming hard slabs up to a foot deep in wind loaded terrain at the upper elevations. These slabs will be difficult to trigger, but the chance remains in very steep, wind loaded start zones. Look for slab formation further down slope and in unusual locations given the recent wind speeds. Triggering a surface slab could step down to deeper weak layers and result in a larger avalanche than expected.

Avalanche Discussion

The Tetons are at the apex of a substantial loading event. Ten day snow water equivalent totals (SWE) are peaking at 4-6 inches. This is a serious load! Warm temperatures and very windy conditions have consolidated the recent snow into a dense slab that is overlying weak facets and crusts on shaded slopes above 8,000’. This slab has gained strength, making it harder for a human to impact the buried weak layers. As a result, signs of instability and human triggered avalanches have been decreasing over the past few days. Don’t be fooled into thinking that the lack of activity indicates a significant decrease in hazard. Weak layers are at peak stress right now and the weight of a rider may be just enough to tip the scales in very steep, upper elevation starting zones. Remotely triggered avalanches were observed 5 days ago and large avalanches were triggered with explosives 3 days ago. The avalanche hazard will slowly decrease during the next few days without snow, but the adjustment process takes time. Conservative terrain choices are recommended for the time being.

Régions couvertes