Bulletin d’avalanche

Tetons

Bridger-Teton Avalanche Center
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Danger d’avalanche

Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 7 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Over a week of snowfall and strong winds has created dangerous avalanche conditions. Soft wind slabs could be triggered on all elevations and on many aspects in starting zones that have been wind loaded. At the mid and high elevations, the chance to trigger deep persistent slabs also continues. Yesterday, no one was injured in two different slides that could have had dire consequences. Outside a backcountry access gate at Grand Targhee, a group of three was caught and carried in a large slide involving a crust near the ground and faceted snow. A member of the party was able to dig himself out and then find find his two companions, one who had an arm sticking from the snow while the other was fully buried. To the south of the Jackson Hole Mountain Resort a slab on a southeast facing slope was triggered by the fifth skier on a slope. This slide involved the recent snow, had a three foot crown and quickly ran down to the flat terrain below. Exercise cautious route finding by identifying wind loaded terrain and by evaluating the snowpack, particularly in areas where the weak basal snow exists.

Problèmes avalancheux

  • Wind Slabs

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

    Strong west to southwest winds have transported snow onto leeward aspects. These slabs will be further loaded today by new snow and strong southwest winds. Backcountry travelers could trigger these slabs with depths up to three feet if they fail on the interface layer buried on January 1st or they could be more shallow if they release on density changes within the recent snow. These slabs can be found throughout steep terrain at the higher elevations and on specific terrain features at the low elevations.

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    Weak snow near the base of the snowpack continues to be a concern. This layer has been further stressed by recent snow and avalanches involving it could release once a slope is impacted by a triggered wind slab or possibly by the weight of a single person or group of people. This layer has been most active on northwest to northeast slopes above 8500 feet but can be found on other aspects as well. Being caught in one of these large hard slabs is likely to have severe consequences.

Avalanche Discussion

A broad trough will be over the state on Thursday. Orographic lift will favor higher snowfall amounts at the higher elevations. Snowfall totals in favored areas could exceed a foot by tomorrow evening. Temperatures will be in the single digits and teens at the upper elevations and in the teens and 20’s at the lower elevations. Westerly winds will gust to 30 to 40 miles per hour on the peaks.At the mid and upper elevations strong winds and new snow will be loading available snow onto leeward aspects and will be increasing the hazard as the day progresses. In steep terrain humans can trigger wind slabs one to three feet in depth on density differences within the new snow and on old snow surfaces that formed in late December. Very large persistent deep slabs up to five feet in depth can also be triggered or release naturally on a basal layer of faceted snow. Up there the general avalanche hazard will be considerable. Pockets of wind slab up to two feet in depth can also be triggered on steep, wind loaded terrain features at the lower elevations where the general avalanche hazard is expected to be moderate.

Régions couvertes