Bulletin d’avalanche

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Danger d’avalanche

Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 7 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Weak layers of snow continue to make human-triggered avalanches possible today. You’re most likely to encounter unstable snow on upper elevation slopes with wind-drifted snow, but sheltered slopes demand your respect as well. Be aware that the weak layers in our snowpack are widespread and difficult to avoid.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    A thin snowpack coupled with major wind events at the end of 2019 have created a different set of persistent slab hazards in the southern mountains than what we’ve been seeing further north. On Thursday a snowboarder remotely triggered an avalanche in Croy Canyon, and on Friday snowmobilers triggered a slide near Couch Summit in the Soldiers. In both of these cases, the snowpack consisted of recent or past wind transported snow atop a weak, faceted snowpack. Yesterday, Chris found identical problems in the out-of-bounds terrain adjacent to Baldy. These problems are illustrated in the video to the right. In the portions of this zone with a deeper snowpack, the same layer of surface hoar that has produced much of the reported avalanche activity this season also exists.

    Persistent weak layers present a complex and frustrating problem for backcountry travelers. They can continue to produce avalanches many weeks after they are buried and they provide fewer and fewer obvious signs of instability as the days without a major loading event pass. They can break wider than you might expect and may be triggered remotely, from gentle terrain adjacent to steeper slopes. Read about my thoughts on how I deal with this type of problem in my personal travels in the Forecast Discussion section found below.

Avalanche Discussion

We are back to that point where we are talking about likelihood and consequences. I understand, for a lot of you it isn’t the most exciting topic. But humor me here, I think it's worth your time. Take a minute, pour a bit more coffee, and follow me through this thought exercise:

What is the likelihood that you are traveling on a slope with buried weak snow? That’s pretty simple this year - it's very likely. What are the consequences of traveling on such a slope? Well, if you are avoiding avalanche terrain, there aren’t any negative consequences. However, if you are in avalanche terrain, the consequences of triggering and being caught in a slide would be quite high. Continued snowfall and wind loading are creating an increasingly thick slab on top of the weak snow underneath. As the slab grows its potential destructive power increases.

But here’s where it gets tricky: What is the likelihood that you might trigger an avalanche on a buried weak layer if you are in avalanche terrain? Well...it’s possible. There are plenty of places where you might trigger a slide and plenty of places where you might not. As I skied yesterday with a friend visiting from out of town I explained this problem to him. I pointed out steep, enticing slopes covered in fresh, soft snow that would have undoubtedly provided us with some fantastic skiing. But we didn’t do anything more than daydream about them. Didn’t even think about it. We avoided avalanche terrain with buried weak layers; not because we thought triggering a slide was likely, but because we knew it was possible.

We skied great snow in low angle terrain, free from the hazards posed by our persistent weak layers. For me personally, the overriding goal is to come home safely at the end of each day. After all, I can’t go skiing tomorrow if I don’t make it out of the mountains tonight.

Régions couvertes