Lawinenlagebericht

Tetons

Bridger-Teton Avalanche Center
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Lawinengefahr

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

Kernpunkte

Recent snow accompanied by moderate winds formed slabs and buried a weak layer 2-3 feet deep that resulted in numerous avalanches. Triggering an avalanche will still be possible today, especially in areas that contain a combination of lingering wind slabs above that weak layer. Careful terrain assessment will be required to identify previously wind loaded terrain and the sensitivity of the buried weak layer across different aspects. Monitor for increased reactivity on slopes that receive sun. 

Lawinenprobleme

  • Persistent Slabs

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

    A significant amount of snow now sits on an old, weak interface composed of facets and crusts created during drought conditions and buried March 20th. Slab depths will range 2-3 feet. There’s uncertainty in the exact distribution of this layer since it was so recently buried. Areas that harbor small facets above a crust will be the most reactive on W, S, and E aspects. Wind loaded terrain will also increase the potential to trigger this buried weak layer. Multiple avalanches triggered remotely were observed during peak loading on the 24th and 25th (Wimpys, KB Ridge, Eddington Canyon). Remote triggering will still be possible today but less likely as sensitivity decreases over time. Monitor the effects of the sun on solar aspects today from W-S-E. An avalanche was remotely triggered yesterday just adjacent to the forecast zone in Mosquito Creek yesterday. 

    Low elevation avalanches will be possible on weak snow near the ground as increased temperatures and sun impacts solar aspects W-S-E. 

    (3/25/2023)

    Large remote triggered avalanche on Wimpys on an E/NE aspect around 9,000' that failed on the March 20th weak interface. 

    Photo: Antonioli

  • Wind Slabs

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

    Sustained W/SW winds above 20 mph two days ago formed soft wind slabs. These slabs will still be reactive today in the upper elevations. Slabs depths will be up to 2 feet deep with 3 feet possible in specific terrain. Areas with the highest likelihood of triggering will be on leeward and cross loaded exposed terrain below cliffs and confined features such as couloirs. Look for obvious signs of instability such as cracking, stiffened or ripple surfaces, and drifts. 

    (3/25/2023)

    Obvious sign of unstable wind slab with deep, large cracking on a wind loaded pocket. 

Avalanche Discussion

Persistent Slab Complexity

The big question on everyone’s mind is the weak interface buried March 20th during the recent storm cycle. This interface resulted in multiple avalanches that were sensitive to remote triggering, which is now depicted as a persistent slab problem. All avalanche activity occurred on easterly aspects where near surface facets lie above a stout crust. A high amount of uncertainty remains in regards to the sensitivity and distribution of this weak layer across different aspects. Continued cold temperatures will slow the process of stabilizing this weak layer, so understanding the consequences of triggering a large avalanche should be in the forefront of your decision making as you travel in the mountains today. Dig down and identify this layer to aid your terrain choice.

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