Lawinenlagebericht

Tetons

Bridger-Teton Avalanche Center
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Lawinengefahr

Wed
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

The snowpack is still stabilizing from the recent storm that brought upwards of 2 feet of new snow and strong winds. With warming temperatures peaking in the afternoon, avalanches could release naturally. Large avalanches are most likely in wind-loaded terrain but are possible on sheltered slopes. The type of weak snow involved can produce avalanches that fail in surprising ways, breaking wider than you might expect. These slides can be triggered remotely—from a distance above, below, or to the side of steep slopes.

Lawinenprobleme

  • Persistent Slabs

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

    The culprit weak layer in recent slides has been a several-inch-thick layer of faceted snow (additional surface hoar included in many locations, free of charge) buried 1.5-2+ feet deep. The distribution of this weak snow remains widespread, and the current sensitivity remains variable. You will most likely find them on slopes facing E-NE-N-NW above about 8000', but avalanches will not be limited to these aspects as the sun moves into play. Assume this layer exists and choose lower-angled slopes that are not threatened by steeper slopes above. You're more likely to trigger persistent slab avalanches in areas where the wind has stiffened the snow surface or formed drifts, but they are also possible in sheltered terrain. Results at JHMR yesterday show extensive activity with 2-5 foot slabs and wide avalanches. To me, this reads that current backcountry slopes are waiting for triggers. With warming temperatures expected up to 10,000 feet, the first clear sign of an unstable snowpack may occur when you trigger a large avalanche. 

    ADDITIONAL DISCUSSIONWarmer temperatures today could lead to wet snow slides and sluffs. These may not be limited to solar aspects as overall air temperatures are climbing. This will primarily be a lower elevation problem where enough snow exists but could creep into the mid and upper elevations. Given the potential for human-triggering, it remains best to stick to lower-angled terrain. Conditions will be most dangerous on middle and upper-elevation slopes during peak warming in the afternoon. Be alert to signs of changing and unstable snow, such as isothermal snow in the middle elevations or cracking and collapsing—these are obvious indicators you've found dangerous conditions.

     

    (12/4/2023)

    This avalanche was triggered by folks yesterday near Windy Ridge.

Avalanche Discussion

Someone must've made a few wrong moves in their powder dance last week and accidentally ordered us some spring temperatures as well. The primary weak layer in question and the new snow slab above it are changing simultaneously and rapidly. Uncertainty and variability remain high. One thing I am confident about is the character of this weak layer and its distribution, and the idea of rapid change or any introduction of liquid water movement makes me cringe. This weak layer is well-developed, showing signs of instability even as natural activity tapers off, is unpredictable, and is capable of producing wide avalanches.

Time is needed for some uncertainty reduction and the temperature swing to play out. The snowpack can't catch a break as tomorrow looks tropical, followed late this week by another wallop of snow. Right now, my mindset rests squarely in the realm of genuine curiosity to see how these conditions pan and keep my terrain choices very conservative. There are several reasons to ratchet it back out there—not limited to the quality of riding decreasing exponentially—and triggering a dangerous persistent slab avalanche is one of them.  

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