Boletín de aludes

Togwotee Pass

Bridger-Teton Avalanche Center
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Peligro de aludes

Fri
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
Sin grado
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Triggering a large avalanche remains possible—especially in wind-affected, upper-elevation terrain. Strong winds have created sensitive drifts in the upper elevations and have added increased weight to buried weak layers and poor structure within the snowpack. Expect to find these in atypical locations, thanks to the strength and direction of the wind. Recent avalanches have been triggered remotely like this one on the East face of Mt. Leidy. Four days ago a large avalanche was remote triggered on Angle Mountain. Cold temperatures will begin to rise today into the mid 20's F. Despite the cold air temperatures it's April, so any period of sun this time of year will drastically alter the snowpack and its stability.  As temperatures begin to warm, cornices that have been building all winter long will begin to decrease in strength. Limit exposure beneath these giants and give them a wide berth while traveling along ridgelines.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1.5–2.5

    Two primary layers of weak snow exist in the top meter of the snowpack. On Tuesday I traveled up West Angle, and near a remotely skier-triggered avalanche, the poor structure was apparent once I dug down into the snow. The most recent snow sits on top of a myriad of facet crust combinations that have recently become reactive, on Angle Mountain and Mt. Leidy. Failures within snowpit tests are easy to obtain and avalanche slopes should be approached with a high level of skepticism of whether the risk is worth the reward. We don't often deal with persistent weak layers so late in a season, and it definitely requires a mindset shift. Triggering a 2-3+' thick persistent slab avalanche still remains a possibility. You're most likely to trigger a slide involving this weak snow on very steep slopes (steeper than about 35 degrees) where the wind has built slabs in recent days and weeks. 

    Deeper weak layers formed earlier in the season composed of crusts, facets, and depth hoar remain a concern. Triggering a wind slab or persistent slab on the March 20th interface could step down to these layers resulting in a large to very large avalanche.

    Recent size D2 Avalanche on Angle Mountain

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Triggering a large avalanche is most likely where the wind has drifted the snow. Tuesday's east winds convoluted an already complex problem, loading atypical areas and thus connecting more terrain to our avalanche problems. Slabs also commonly form below cliff bands, on the aprons below steep couloirs, or at the base of cliffs where spindrift accumulates. Watch for evidence of windblown snow such as pillowed areas, dunes or ripples, or denser snow at the surface. Today's warming temperatures may increase the reactivity of these wind slabs, and they may step down into buried weak layers (see above), producing an even more dangerous avalanche.

Avalanche Discussion

There is a saying that spring is a battle between winter and summer. While winter has been steadily winning rounds in this year's boxing match, it may be taking a seat as we begin a warming trend today that will likely begin to affect the stability of our snowpack.  As we transition from this stormy period into the beginnings of high pressure, wind slabs now can be found across the compass rose from shifting wind directions, all with the potential to stepping down to our persistent weak layer. Furthermore as winter sits down in the corner for a break, the emergence of the sun and rising temperatures will quickly destablize the surface snow. After a deep and long winter it's hard to imagine it's already the first week of April. Keeping that in mind, don't fall trap to winter's slumber and be aware of your surroundings even if you are seeking sheltered and drier snow - making sure you are out of the way and not under steep solar avalanche paths as the spring shed cycle begins. The same goes for cornices, give these a wide berth and be wary of hanging around slopes where these monsters lurk above you.

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