Bulletin d’avalanche

Snake River Range

Bridger-Teton Avalanche Center
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Danger d’avalanche

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

Points saillants

Recent snow and wind are creating dangerous avalanche conditions. Human-triggered avalanches breaking 1-3 feet deep are likely in wind-loaded terrain as well as areas more sheltered from the wind. Sticking to lower-angled slopes remains your best approach. Recognize that you could trigger avalanches from above, to the side, or below steeper slopes.

Problèmes avalancheux

  • Storm Slabs

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

    Over the past 48 hours, this storm has deposited ~16-20 inches of snow in the Snake. This recent snow is settling and creating a cohesive slab in many locations, including some rare low-elevation terrain that happened to harbor older snow. Taking a peek at recent observations denotes a reactive problem on the new/old snow interface,  buried ~1-2 feet deep. This weak interface is easy to find in snowpack tests; dig to add this data point to your decision-making and terrain choices, and carefully evaluate the snowpack as you change aspect and elevation. Every slope harboring older snow should be presumed guilty until proven innocent. Given the potential for human-triggering, it remains best to stick to lower-angled terrain.

     

    (12/15/2024)

    Around 16-20" of new snow has fallen on a weak interface of older snow in the Snake. Observers noted cracking and widespread collapsing. 

  • Wind Slabs

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

    Moderate to strong winds (gusting over 40mph) out of the south/southwest increased yesterday, forming slabs 2-3+ feet thick in exposed terrain above ~9,000’. The higher one moves in elevation, the thicker and less predictable these slabs may be and the larger the avalanche they can produce. You’re most likely to encounter this problem where a stiff wind-loaded slab sits over old snow at upper elevations. Rippled or dome-like features indicate that you've found a wind slab. Even without these signs, fresh drifts are wise to avoid, especially in higher consequence terrain.

    (12/15/2024)

    This large avalanche was remotely triggered in Christmas Tree Bowl in a zone bordering the Snake and with a similar snowpack structure on 12/15 on the surface hoar on the old/new interface. 

Avalanche Discussion

It's finally looking like winter after weeks of high pressure. The current challenge remains that when it snows and blows, the avalanche danger goes up. Weeks of clear weather have created a weak interface between the new and old snow. This interface is being tested by this continuing storm on both northerly and southerly slopes, though in spottier distributions on southerly. We can still enjoy the fresh powder by sticking to simple terrain and lower slope angles and ruling out steep, upper-elevation slopes that have seen more wind. Very steep, sheltered slopes also need an extra dose of caution. The season is still young, and now is a great time to practice good habits that stick—like measuring slope in the field vs. relying on slope angle shading on a map. We currently have a ton of primary bullseye information, including recent avalanche activity, continued reports of collapsing, and poor test scores. But it all points to the same conclusion—we have a tricky snowpack currently. As you move in the mountains, look for those surefire indicators that the new loading is bringing weaker snow close to the edge. 

Régions couvertes