Boletín de aludes

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Peligro de aludes

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

Lo esencial

It is unlikely that you will trigger an avalanche today. Chances remain highest in steep, rocky terrain on northerly, where slabs could be 1-3 feet deep. Although the possibility of triggering an avalanche is unlikely, the consequences could be high in terrain where you get strained through trees and rocks or pushed into terrain traps. 

Problemas de aludes

  • Persistent Slabs

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

    Triggering a slab avalanche is unlikely but not impossible. Weak layers buried 1-3 feet below the surface continue to show the potential for propagation in snow pits. A size D2 avalanche was triggered by snowmachiners 4 days ago on a steep north aspect near 10,000 feet. This avalanche was three feet deep and is an example of an isolated terrain feature with the potential for avalanche activity, most likely failing in a wind-affected zone. Wind-affected and rocky terrain on steep, shady slopes is where you might encounter a thin spot in the snowpack, which is the most likely place to trigger an avalanche. Getting caught and carried could be traumatic, given obstacles below the surface. Dig down to confirm or deny weak, sugary snow as you travel.

    A north facing slope near 10,000 feet with a start zone in wind-affected snow.

    (12/30/2023) Photo: Shane Copeland

Avalanche Discussion

Today, the message remains the same. With no significant loading in over three weeks, the snowpack has had time to adjust, and avalanches are unlikely but not impossible. Do not get complacent and use safe travel practices (one at a time through suspect terrain). Be wary of steep terrain with thin spots, wind-affected snow, or terrain traps where weak, sugary snow at the base of the snowpack could catch you off guard in consequential terrain. The dry spell has transformed the top 6 to 8 inches into soft, cohesionless facets (recycled powder) on shady aspects, making the riding enjoyable.  Steep solar aspects have crusts and there is widespread surface hoar. None of these surface conditions bode well for stability with the incoming snow load.

Thankfully, it appears as though we have an exit from Groundhog Day. The prolonged dry spell that began over three weeks ago will close tomorrow as northwest flow moves into place with an increased chance of snow through the weekend and into next week. While we were all hoping for a large storm with lots of weight to flush away the weak structure in the snowpack, this storm cycle looks more like slower, incremental loading over multiple days.  It will be challenging to predict when the new load on the current weak structure will reach critical mass. However, we do know that there is an abundance of weak surface conditions that have the potential to fail quickly under a new load. Perhaps more importantly, we know that the December slab that sits over weak, sugary snow from November has continued to show propagation in snow pits despite a lack of avalanche activity. We might need a little more water weight to tip the balance. How much weight needs to be added to the snowpack for us to start seeing avalanches fail at the November drought layer again? Will we get enough weight by next week to see natural avalanches fail on November facets, or will the persistent slab problem remain stubborn if this storm doesn't produce as much as we all hope for? What other problems might develop?

As we head into the next storm cycle, prime your brain to continue looking for red flags and clues (cracking, whumphing, storm totals, wind loading...) that will help answer these questions. And please continue to send in your observations.

 

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