Lawinenlagebericht

Soldier & Wood River Valley 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 7 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Triggering large, 1-3 foot thick slab avalanches continues to be a possibility. Buried weak layers underneath these slabs produced natural avalanche activity last week. To reduce your risk, choose gentler slopes and avoid terrain where the wind has built slabs and added stress to the weak snow below. In upper elevation terrain, be on the lookout for thin, recently formed drifts of wind-blown snow that may be sensitive to the weight of a skier or rider.

Lawinenprobleme

  • Persistent Slabs

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

    A variety of persistent weak layers exist on most slopes in this zone, generally buried 1-3 feet deep. Crusts with facets, depth hoar, and surface hoar have all produced avalanche activity here, and periodic storms aren’t giving the snowpack time to heal. As time passes, the likelihood of triggering one of these slides is decreasing, but this process is happening slowly. 

    When dealing with persistent weak layers like these, here are a few approaches to reduce your risk:

    1. Avoid recently and previously wind loaded terrain. In these areas, slabs are adding stress to the weak snow buried underneath and providing a stiff layer of snow to help fractures propagate through the snowpack.
    2. Be aware of the direction that the slope you are on faces. Last week’s avalanche activity in this area was more common on slopes where the sun had built crusts.
    3. Keep an eye on the terrain you are traveling through and underneath. Avalanches are most likely on slopes between 35-45 degrees of steepness. However, persistent slab avalanches can be triggered remotely — from below or to the side of steeper slopes.

    ADDITIONAL DISCUSSIONYesterday’s storm brought 1-5” of new snow to this zone. While this area recieved the least snow yesterday, it saw the strongest wind. I expect any wind slabs that you might encounter today will be isolated to exposed, upper elevation terrain. These slabs are likely to be more touchy where they are sitting on icy crusts or slick, alpine surfaces.

Avalanche Discussion

I like to think about the snowpack as a record of a season’s worth of weather, written in snow and ice. Thinking about it this way helps me to understand it as a dynamic animal, instead of a static, unchanging object.

Because of this, the snowpack is a different animal every year. Some years are marked by generally good stability and relatively easy to assess and manage avalanche problems. Other years have us traveling through the mountains with the hairs on the backs of our necks raised. If you’ve been out and about this season, you know that we’ve found ourselves in the later category. The depth of the snowpack varies considerably across our region, but we have a variety of persistent weak layers of snow across the board. 

In our northern areas, where the snowpack is deeper, triggering an avalanche involving this weak snow is less likely, thanks to the thick slab of snow on top of it. Picture a well-armored, sleeping dragon — you can walk in a lot of places without waking up the beast, but if you find the chink in her scales (thin trigger point), you find yourself facing an unsurvivable problem.

In our southern areas, where the snowpack is thinner, we are dealing with the flip side of this equation. Avalanches here will be smaller, thanks to the thinner slab that would be involved. But, you’re more likely to find a trigger point because the weak layers are closer to the surface. And notice that I said “smaller”, not small. The consequences of triggering one of these slides can be high, particularly in areas where you would be carried through trees or swept into an abrupt terrain trap where avalanche debris can pile up more deeply.

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