Bulletin d’avalanche

Banner Summit

Sawtooth Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Dangerous avalanche conditions exist. A widespread layer of weak snow is buried beneath a 2-3 foot thick slab on most slopes, and triggering an avalanche involving this weak snow is likely. Slides may be triggered remotely—from long distances away from steeper slopes. Pay attention to the terrain around you and above you. Cracking and collapsing of the snowpack are clear indicators that the snowpack you are traveling in is unstable.

Problèmes avalancheux

  • Persistent Slabs

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

    The recent storm deposited 2-4' of snow (2.5-3.1" SWE) across this zone. This snow fell on an exceptionally weak layer of snow made up of crusts, facets, or a combination of the two. This combination produced a widespread natural avalanche cycle, with slides observed on all aspects and at all elevations. You'll find this combination of a thick slab overlying a reactive weak layer almost everywhere you go today. The slab of new snow is thick enough that the wind doesn't need to have done any work to build a slab—avalanches are possible in both sheltered and wind-affected terrain. 

    Thanks to this ugly weak layer + slab combination, the possibility of remotely triggering avalanches is very real. A collapse on mellow terrain at the valley floor can quickly travel long distances and release avalanches on steeper slopes far above. Pay close attention to the terrain around you and above you. Remember that there are other people out in the mountains and that impacting them and being impacted by them is possible. 

    ADDITIONAL DISCUSSION: An uptick in wind speeds was recorded at some weather stations overnight and fresh slabs are likely forming as I write this. The wind will continue to transport snow and build slabs until things calm this afternoon. These thin, fresh slabs may be particularly sensitive today, but they will be relatively small. Most importantly, they are adding load to the weak snow underneath and can act as triggers for the slabs described above.

Avalanche Discussion

As of this writing, we are just 36 hours out from a major storm and an Avalanche Warning. 1.5-3.5 feet of snow fell on a very weak snowpack and widespread natural avalanche activity occurred.  Conditions remain touchy and I will be more surprised if we don't hear about human-triggered avalanches today than if we do.

A healthy dose of sunshine and a fresh blanket of snow will make today a beautiful day to be in the mountains. That same combination can distract us from the hazards posed by our snowpack. Add in the fact that for many of us we are just starting our skiing and riding season and it's a safe bet our skills for traveling in avalanche terrain are a little rusty. I encourage you to enjoy our early-season powder with a giant smile on your face, and to do so with the knowledge of what's underneath you. Make a plan before you head out and take some pauses along the way to remind yourself of that plan. Communicate with your partners about what you are seeing in the snowpack and talk about the terrain around you and above you. The snowpack doesn't care about you, but I sure do; enjoy the early-season snow and remember that all great days end when we arrive home safely at night. 

Régions couvertes