Lawinenlagebericht

Togwotee Pass

Bridger-Teton Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
Keine Stufe
Open full map
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Kernpunkte

Recent snow with west/southwest wind has formed slabs 1-2 feet deep and stressed weak layers buried 2-3 feet deep making human triggered avalanches possible. Avalanches will be most probable on very steep, complex, and wind loaded terrain. Choose less consequential terrain to manage the uncertainty associated with the large amount of snowfall from the recent storms.

 

Lawinenprobleme

  • Wind Slabs

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

    Over the last week Togwotee has received 20-24 inches of snow. This snow was accompanied by west-southwest wind forming slabs 1-2 feet deep on wind loaded slopes. These slabs will be less reactive tha previous days, but still possible to trigger an avalanche today. Look for signs of instability such as cracking. Be on the lookout for indications of recently wind loaded terrain including cornice formations, large pillows/drifts, and stiffened or hollow sounding snow. Wind loaded terrain also overlaps where the most persistent slab avalanches have been triggered on north-east aspects. 

     

    (2/1/2025)

    Reactive small slabs on wind loaded slopes failing on the new to old snow interface comprised of facets. 

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    Weak layers in the middle of the snowpack buried 2-3 feet deep remain possible to trigger on very steep slopes over 35°. Slab depths on wind loaded terrain could be up to 4 feet deep. Signs of instability such as cracking, collapsing, or recent avalanches may not be present before triggering a large, dangerous avalanche that is capable of propagating far across or upslope.  This problem has been more pronounced on north through east aspects above 7500’. Multiple tracks on a slope may not indicate that a slope is stable. Stick to lower consequence terrain away from terrain traps and rocky, convex, very steep slopes while the snowpack heals after being rapidly loaded by a large amount of snow. Any heavily wind affected terrain where the overlying slab depth varies should be approached cautiously. 

    (1/16/2025)

    An example of terrain where persistent slab avalanches are most likely.

    Photo: Bridger-Teton Avalanche Center

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–3

    Weak snow buried around 5 feet deep exists near the ground above 9,000’. Although triggering an avalanche at this depth is very unlikely, it's not impossible. On February 10th, a rider stepped off their sled and triggered a very large avalanche that failed near the ground on Lava Mountain. This avalanche was triggered where the overlying slab was thin making it possible for the rider to impact the underlying weak layer. Manage this problem the same way you would manage weak layers in the middle of the snowpack (problem #2) by avoiding very steep, rocky, and heavily wind-affected terrain.

     

    (2/11/2025)

    The crown of the recent unintentionally-triggered avalanche on the E face of Lava ~10,400'.

    Photo: Bridger-Teton Avalanche Center

Avalanche Discussion

Heightened Avalanche Conditions Despite the Drop in Danger Rating

A series of storms from February 14-19 produced a heavy amount of snowfall. Observations during this period were few and far between due to difficult travel and poor visibility. Any observations were direct action related to new snow instability (and deep powder riding in lower angle terrain). Now that the weather has settled down it is important to assess how the snowpack has adjusted to the stress of adding 2-4.5” of snow water equivalent to a snowpack riddled with weak layers buried at the beginning of February. We haven’t had any reported avalanches stepping down to weak layers. This is a good sign, but we aren’t totally clear yet. Human triggered avalanches may still be possible, especially on steeper avalanche prone slopes. Wind slab or persistent slab avalanches are a concern, especially where they overlap. Slopes that avalanche more regularly should certainly be avoided today. Over time, buried weak layers will adjust to the load and become more stubborn, but this process is slow and takes time. Every day is only incrementally safer than the last. For this reason, it is best to keep it more conservative today and avoid slopes where the consequences of triggering an avalanche will be more severe above trees, rocks, or terrain traps.

Avalanche incidents are common on days with Moderate danger, especially the first day the danger has been dropped. 

 

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