Bulletin d’avalanche

Tetons

Bridger-Teton Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Human-triggered avalanches are possible on slopes where the wind has built slabs on top of weak layers in the snowpack. Slabs failing on weak layers in sheltered terrain are less likely but can't be ruled out entirely. You can reduce your risk by avoiding thinner areas in the snowpack at middle and upper elevations. Carefully evaluate the snow for depth and the presence of a buried weak layer.

Problèmes avalancheux

  • Wind Slabs

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

    Many small wind slab avalanches where observed 24-48 hours ago. In the past 24 hours, moderate wind shifted to the north and has likely loaded and cross loaded aspects with a southern component.  Wind slabs formed from light to moderate, variable winds may remain reactive underfoot today. Wind-affected areas can be identified by drifts, cornices and pillows along ridge crests, or stiffened snow surfaces. Recent snowfall and cold temperatures have allowed loose snow to accumulate beneath cliff faces and gullies. These sluff piles can be triggered much the same way as smoother wind slabs and may also add strain to buried weak layers.

    (1/18/2023)

    Thin wind slab on Buck Mountain, possibly triggered by loose snow sluffing down from the  steeper area above.

  • Persistent Slabs

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

    Weak layers of faceted snow lie buried three or four feet or more below the surface in most terrain above 8,000'.  Triggering a weak layer in locations where the snowpack is that thick is unlikely, though the resulting avalanche would be very large.  In other areas with a thinner snowpack, the weak layer could be more easily triggered. Mountain passes or saddles, steep, rocky faces and other areas where strong wind has stripped should serve as waypoints for caution. Here the weak layers lie closer to the surface and within range of the force of a passing skier or rider. Triggering the weak layer could cause a crack that involves much thicker slabs and result in a very large avalanche. The recent avalanche on Albright Peak  with a crown height that tapered from one foot to five feet is an example of this setup for an avalanche. Note the pillows of snow and drifts flagged in the lee of trees indicating the wind-loading patterns on this exposed slope. Seek out more sheltered, lower angled terrain with a thick snowpack to reduce your exposure to this avalanche problem.

    (1/16/2023)

    This avalanche was triggered on a west aspect off of Albright Peak around 10,200 feet.

    Photo: C. Martin

Avalanche Discussion

Great skiing and riding exists throughout the Tetons without tangling with the terrain most likely to produce an avalanche. Signs of instability are not so obvious at the moment though if you pay close attention, probe for snow depths, dig on the aspect you want to ride and generally avoid the problem areas listed below, you can still have a safe day. 

Be wary of entering avalanche terrain that has most or all of the following characteristics:

  • Wind-affected alpine or near-treeline terrain above about 9000' in elevation. This does not exclude typically windward slopes. These areas have seen recent consistent snowfall and differing wind patterns that have created a complex pattern of scoured and loaded slopes, likely resting on a far thinner snowpack relative to other slopes in the area. 
  • Slopes with rocks poking through the snow and variable snow depths due to uneven terrain
  • 35-45 degrees in steepness
  • On the southern half of the compass (east-south-west)

 

 

Régions couvertes