Lawinenlagebericht

Tetons

Bridger-Teton Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Strong westerly winds have formed sensitive slabs up to a foot deep in exposed terrain at the middle and upper elevations. Cracking, “punchy” surfaces, and smooth pillow features are all signs of unstable wind drifted snow. Although unlikely, deeper avalanches failing on persistent weak layers could be initiated by large triggers such as a wind slab or cornice failure.

Lawinenprobleme

  • Wind Slabs

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

    Sustained and strong westerly winds gusting up to 60 mph have redistributed snow and built sensitive slabs up to a foot deep in exposed middle and upper elevation terrain. Wind directions over the past several days have been variable (SW-NW). As a result, slabs have formed on a variety of aspects. Suspect features include leeward terrain off exposed ridges, cross loaded gullies, and aprons below cliff bands. Be on the lookout for wind affected snow on the surface that is stiff or drifted. These slabs will be dense given the intensity of the wind. Probing the snowpack for hardness changes (hard over soft) or digging a quick “hasty pit” are useful ways to identify these slabs. Sheltered terrain will provide the safest riding.

    Cornice Falls: Observations of cornice failures continue to be reported. Give cornices a wide margin and be careful along ridgelines as they can break further back than expected. Falling cornices can impact deeply buried weak layers and trigger large avalanches.

    (2/23/2024)

    Wind slab avalanche triggered outside of JHMR in the backcountry at 9700' NE aspect. 

  • Persistent Slabs

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

    Hard slabs 3-5 feet thick overlay weak snow that formed earlier in the season. Steep, rocky, unsupported, and wind affected terrain on the north half of the compass has proven itself to be most suspect. Thin spots in the slab (trigger points) are most common in these locations. While it has become unlikely for a human to trigger one of these slabs, larger triggers such as cornice falls, smaller avalanches, or even snowmobiles still have the potential to impact weak layers buried deeply in the snowpack.

    The last avalanche involving persistent weak layers was triggered by a large cornice fall on 2/21. The last human triggered avalanche on these layers occurred on 2/10.

    (2/17/2024) Photo: Teton County SAR

    The avalanche on No Name peak is a reminder of the destructive power of an avalanche failing on a deeper weak layer. This one required a very large trigger - either a cornice fall or possibly a smaller avalanche. 

Avalanche Discussion

After a nice stretch of relatively calm weather earlier this week, wind has returned to the mountains. Winds really kicked up yesterday and last night with the Rendezvous Mountain weather station recording over 600 total miles of wind in 24 hours (a lot of wind). Yesterday, we received multiple reports of drifting snow and small, yet sensitive slabs being formed in exposed terrain. Winds are only expected to increase in intensity throughout the day. Expect conditions to be “touchier” today than yesterday despite the continued Moderate danger rating. Remember that being caught and carried in a small avalanche can have serious consequences in extreme terrain. An incoming storm that is expected to arrive tonight will increase the avalanche hazard tomorrow.

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