Lawinenlagebericht

Tetons

Bridger-Teton Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
Keine Stufe
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Avalanche conditions remain dangerous. Triggering a large avalanche that can bury a person is possible in steep terrain. Many recent avalanches are proof of this. Conservative decision-making and low angle terrain choices are the best way to avoid triggering a dangerous avalanche.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2.5

    Triggering a hard slab avalanche 2-4 feet deep is possible in steep terrain. These avalanches are most likely to occur above 8,000’ on north through east facing slopes. However, any steep slope that held snow prior to the 12/1 storm should be approached with caution as the structure is likely poor. Triggering one of these avalanches is becoming more difficult and may not occur until you have committed to the slope. This recent avalanche in Moose Brush broke above the rider on a slope that had existing tracks on it. The snowpack remains sensitive to human triggers. If you do collapse the weak layer, the resulting avalanche will likely be large.

    Digging and probing are great ways to evaluate the snowpack. If you press your ski pole through the snowpack and it suddenly drops with little resistance, then chances are you’ve found a location where triggering a persistent slab avalanche is possible. While evaluating the snowpack can help identify problem areas, persistent slabs are unpredictable and dangerous. The best way to avoid triggering a large avalanche is to steer clear of steep terrain (greater than ~30°) altogether today.

    (12/10/2023)

    Human triggered avalanche in Avalanche Bowl. The crown is about 3 feet deep.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Moderate winds out the west/southwest were blowing in the mid 20’s (mph) at the upper elevations yesterday morning. Snow was redistributed in exposed upper elevation terrain and formed soft slabs up to a foot deep on some leeward (SE-E-NE) aspects. These wind slabs are not widespread and are most likely to occur in very steep, wind affected terrain above 10,000’. Watch out for areas where the snow feels “thicker” or “punchy” and avoid terrain with obvious wind drifts. It is possible that a wind slab triggered on the surface could step down to weak layers buried deeper within the snowpack resulting in a large avalanche.

    Evidence of wind loading yesterday. Note the wavy texture of the snow surface

    Photo: Noah McCorkel

Avalanche Discussion

A weak early season snowpack has been put to the test and failed. Since December 1st, roughly 50” of snow with 4” of snow water equivalent (SWE) has fallen on top of weak, faceted snow that formed during the November drought. These loading events have added a great deal of stress to buried weak layers resulting in numerous natural and human triggered avalanches. Large (D2) avalanches have been reported nearly every day since the storm cycle began. 

Obvious signs of instability such as cracking, collapsing, and remote triggering are decreasing in frequency. This creates a dangerous situation as the snowpack is not providing us with clues until it is too late. We are entering a period where it is possible to ski out onto a slope, make a few turns, and then trigger a large avalanche that breaks above you. Don’t be fooled by the quieter nature of the snowpack, many slopes are just waiting for a trigger. Another skier triggered avalanche reported yesterday in Avalanche Bowl is proof of this. Cautious route-finding and conservative terrain choices are critical in order to stay safe today. The only surefire way to avoid triggering a dangerous avalanche is to steer clear of steep terrain, especially where it is rocky and rolls over like a basketball. Seek out ridges and low angle slopes to maximize safety and enjoyment.

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