Boletín de aludes

Togwotee Pass

Bridger-Teton Avalanche Center
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Peligro de aludes

Wed
Alta montaña
1 · Débil
Límite del bosque
1 · Débil
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

Prolonged dry weather has caused a decrease in the likelihood of avalanches. Vigilance is always warranted in avalanche terrain, and there remains a remote chance of triggering a slide 1-3 feet deep, particularly on shady slopes.

Problemas de aludes

  • Persistent Slabs

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

    On 12/30, a snowmobile-triggered avalanche was reported on a north aspect at 9,800 feet near Gunsight Pass in the Wyoming Range.  This avalanche failed in a wind-loaded area on weak snow 3 feet beneath the surface.  

    This avalanche is a good reminder to continue to look for areas of potentially unstable snow.  Remember only to expose one person at a time, use islands of safety, and watch your partners when entering avalanche terrain. The reporting party of this incident followed safe travel practices, which prevented injury and burial. 

    (12/30/2023)

    Snowmobile triggered avalanche on a north aspect at 9800'. Triggered by rider topping out on the slope. No one was caught or carried in this avalanche.

    Photo: Shane Copeland

Avalanche Discussion

The snowpack structure is poor in many locations. When advising people on miles of snowy mountain terrain, you want to be sure you're not missing anything in the bigger picture. Messaging low danger with a persistent slab problem is tricky, just ask Colorado. So I did just that to discuss the current structure, the continued moderate to strong results in snowpit tests, and the lack of avalanche activity. 

The boxes we can check:

  • No obvious signs of instability. If you experience cracking or collapsing—do not pass GO! But it's been several weeks since reports of these signs in avalanche terrain have come in. Given the current setup, the recent triggered slide in the Greys Zone illustrates the possibility of encountering instability.  
  • Time without loading. Our last significant loading event was well over a week ago.
  • Periods of temps near freezing. And not because they are healing anything, but rather because it is preferable to see if a weak layer can withstand a few days of warmer temps.  

The boxes we cannot check:

  • Physical signs of change. The best way to heal a weak layer is to compact it beneath a heavy snow slab. But even where 12/1 has been buried by a heftier slab, the physical properties of this weak layer have looked the same, remaining relatively thick and dry and propagating cleanly in tests.
  •  Improving snowpack test scores. Pits are great at telling us when things are unstable but not so good at predicting overall stability.  This category remains inconclusive to me, but brings me pause (and should bring you pause, too). 

The prolonged dry weather since early December has left us with a widespread weak, faceted snowpack. On most slopes that aren't steep enough or due solar and haven't been cooked by the sun, the top ~8 inches of the snowpack have faceted and turned sugary and cohesionless.  While the shifting weather pattern will open the door to instability, the forecasted snowfall over the coming week is not looking as promising as it once did. As usual in the business of avalanches, only time will tell.

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