Bollettino valanghe

Togwotee Pass

Bridger-Teton Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Triggering an avalanche 2-3 feet thick is possible on steep slopes at all elevations. Use caution where the snowpack is thinner - especially in rocky areas and on wind-affected snow. Watch for shallow slabs where recent winds have transported new snow. Intense sun and warm temperatures may cause loose snow avalanches on slopes that directly face the sun. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    The persistent slab problem is found on all elevations and primarily on west through north through east aspects. The snow at the base of the snowpack remains weak and is now 2-3 feet below the surface. Use caution around steep, rocky, or wind-affected terrain. These areas often have a thinner snowpack, increasing your likelihood of impacting a buried weak layer. As you travel, take time to dig or probe to identify snow depth and the presence of weak layers. Hard snow over soft snow indicates weak snow buried in the snowpack. As temperatures rise through the day, weak layers in the snow will become more sensitive to triggering. This avalanche was triggered around Februrary 20th during an initial warming phase demonstrating how warm temperatures can impact buried weak layers. When in doubt, stick to low-angle terrain under 30 degrees. 

    Cornices can break unexpectedly and may act as a large trigger impacting deep weak layers. As temperatures rise through the day, the likelihood of triggering a cornice or slab increases. Minimize time spent on slopes with cornices overhead.

    A persistent slab avalanche on a SW aspect at 9800 feet, most likely triggered on Feb 20th during a warming trend. (2/22/2024)

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Moderate winds over the past 48 hours have created fresh soft slabs less than one foot deep. You may find wind slabs 1-2 feet thick in isolated areas along ridgelines in high-elevation exposed terrain - particularly on east-facing slopes. Stay alert for signs of wind-affected snow such as cornices, pillows, and stiff drifts.  Watch out for convexities, gullies, and exposed terrain where winds are likely to deposit snow.  Shooting cracks are a good indicator of unstable snow conditions. 

    Cornices have continued to grow and you can break them without warning. Direct sun and warm temperatures may weaken large cornices that have formed throughout the season. Cornices may break further back than expected and have the ability to trigger a larger slab avalanche. Give ridgelines plenty of space and watch for slopes with cornices hanging overhead.

    (2/13/2024)

    Togwotee Pass roadside terrain trap, 9100', north aspect wind loaded. D1.

    Photo: Travis Baldwin

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Clear skies and warm temperatures will decrease stability on southerly aspects by the afternoon - particularly slopes protected from winds. As solar influence on snow surfaces becomes stronger later in the year it can quickly heat surface snow. Watch for snow surfaces to become wet and easier to penetrate as a sign of wet loose avalanche potential. The snow around rocks and cliffs will warm up earlier in the day.

     

Avalanche Discussion

Today we are expecting another beautiful day in the mountains. With clear skies and warm temperatures, it will be a beautiful day for riding. Winds have picked up over the past day and light snow from previous days is getting blown around the mountains. Shallow soft slabs may be present in a variety of terrains and on any aspect. These will be in conjunction with thicker stiff wind slabs that are present on higher elevation exposed ridgeline. In addition to our winds, solar input will be of concern today. Direct sun with high temperatures may create surface snow instabilities. Winds will help to keep surface snow cool, but solar slopes that are protected from the wind will heat up quickly. These instabilities tend to follow the sun through the day starting in the east and moving west as the day progresses. Checking snow surfaces for wet snow throughout the day can help you identify the possibility of wet loose avalanches.

As the days get longer, and the sun higher in the sky we have more time to play in the mountains and enjoy the large amounts of snow that fell this month. These longer days also mean more direct solar input on our snowpack. We are likely to see more and more avalanche problems related to heating. Now is a good time to read up on wet avalanches and think about the decision-making process surrounding them. 

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