Lawinenlagebericht

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Triggering a large avalanche in very steep, rocky, wind-affected terrain remains a possibility. You can greatly reduce your risk by steering clear of slopes with these terrain characteristics. Continue to follow safe travel protocols, even as the Avalanche Danger decreases—carry your rescue gear, travel one at a time in avalanche terrain, and keep your eyes on your partners. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    This zone sits in the "sweet spot" for hosting a lingering persistent slab avalanche problem. Here, the weak layer of snow near the ground is well developed and exists in many locations. The slab overlying this weak layer is thinner than in the zones to the north and west, which makes it easier for the weight of a skier or rider to trigger. For these reasons, triggering an avalanche that fails on this weak snow remains a possibility today.

    The weak snow responsible for this problem was buried in early December on middle and upper elevation slopes that face away from the sun. You are most likely to trigger an avalanche that fails on this snow in very steep, rocky, wind-affected terrain (see photo at right/above). Here, the overlying slab is variably thick which gives you "better" access to the weak snow underneath. 

    This large, natural avalanche released naturally near the end of the last storm in very steep, rocky, wind-loaded upper elevation terrain in the 4th of July drainage in the White Cloud Mountains.  

Avalanche Discussion

As the danger drops we often find ourselves seeking out steeper terrain. Here, even minor problems can carry high consequences. Be on the lookout for the additional problems described below and think about the potential consequences of encountering them in the terrain you are in:

  • Wind Slabs: thin, isolated wind slabs exist in upper elevation terrain. These slabs are generally well-bonded to the surfaces that they are resting on and are mostly just decreasing the skiing/riding quality where they exist. However, if you find one sitting on a layer of icy snow with facets you may still be able to trigger it.
  • Cornices: Cornices have grown to impressive sizes already this year, which is unusual for January. In my recent travels in the mountains, I've seen lots of giant cornices that are yawning off the steep terrain that they are attached to. In many places, large cracks and crevasses exist between the ridgeline and the cornice itself. Even just falling into one of these could have some nasty consequences. Large cornice failures can be very effective triggers for the deeply-burried weak snow described above.
  • Wet Loose Slides: The natural cycle of wet loose (point-release) activity has largely run its course at this point. However, with overnight temperatures hovering around freezing in the mountains it won't take too much sun to melt the crust that formed on the snow surface. If you are playing in very steep, rocky terrain that directly faces the sun during the heat of the day you might be able to push some of this wet surface snow into a small slide. 

Here's a challenge for you for today: when you head out into the mountains, I'd like you to think about the snow surfaces that you are traveling on and how they might behave if we threw a big storm at them. We spend a lot of time talking about weak snow in the snowpack, but these layers don't just spontaneously appear. They typically form at the surface and are buried by subsequent storms. Right now we are in a period of weak layer creation. At a certain point, we will be burying these layers. Be on the lookout for crusts, faceted snow, and surface hoar in your travels today. If you can find all three of these in one location there will be a mind-blowing prize for you! Take a photo and send it to me at [email protected] in order to claim your prize! (Forecaster's note: there is no prize, but I can guarantee an excited email in response.)

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