Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Wed
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 7 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Isolated areas of unstable snow may exist on very steep slopes, particularly at elevations above 9,000'. Be on the lookout for areas where old stiff, wind-drifts overlie weak, sugary snow near the ground.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–2

    There is a reason that the avalanche danger is LOW in this zone - it just refuses to snow down here. The "favored" portions of this zone have tallied 2" of snowfall in the past 2 weeks. The last significant reported avalanche took place 12 days ago when ski patrollers at Bald Mountain intentionally triggered an avalanche during avalanche mitigation work. The slide failed on a heavily wind-loaded slope with weak, sugary, faceted snow in the lower part of the snowpack. When you're out in the mountains today, this is precisely the type of scenario that you should be looking for: strong, dense slabs of wind-drifted snow sitting on top of weak snow near the ground.

    If you're on skis or a board, try to push your pole to the ground and see if you can feel a change in resistance as you do. If you are struggling to push your pole into the snow and then all of the sudden the last bit to the ground has almost no resistance you've likely found an area where a hard slab is sitting on weak snow underneath. If you're out riding and are getting bucked around on hard snow, struggling to keep your sled cold you are likely on a hard slab of wind drifted snow. Then, you look over and that one buddy of yours who always gets his sled stuck (we've all got one) managed to punch through the hard slab and the tail end of his sled is sitting on the ground. The sugary snow near the ground that his track is spinning against is the weak, faceted snow that we are talking about here.  

Avalanche Discussion

The winter of the haves and the have nots continues. If you frequently ski or ride in this zone, you know that you are in the latter category. The recent storm brought 1" of snow to the furthest west portion of this zone and nothing at all to the rest of the area.  This pattern has been present for much of the winter and has "helped" to generate the ongoing persistent slab problem that we're stuck with. For weeks we've been warning you about the sort of terrain where you are likely to encounter this sort of problem: steep, wind-affected, and alpine. Let's take a minute to look at why these sorts of areas are more problematic.

  • Steep: As a slope gets steeper, gravity is pulling down more intensely on the slab. Slopes in the 35-45 degree range are at the sweet spot, where it isn't so steep that the snow just sluffs off, but it is steep enough for gravity to have an appreciable downward force on the snowpack. 
  • Wind-affected: The wind plays two roles to increase the likelihood of triggering slides. In areas that are more commonly scoured, the snowpack is thinner and the weak layers are closer to the surface and easier to impact. In areas that are loaded, a stiff, dense slab of snow is stressing the weak snow underneath. Oftentimes these areas exist right next to each other, creating a scenario where likely trigger points are adjacent to meaty slabs. Not good.
  • Alpine flavor: Upper elevation terrain is typically steeper and more wind-affected than terrain lower on the mountain. In addition, this sort of terrain commonly has lots of scree piles, rocky ribs, and cliff bands. These features help to create lots of thin spots on the snowpack where weak layers are closer to the surface and easier to impact.

Spend some time scrolling through our media gallery and look at some of the deeper avalanches that we've been seeing this season. Try to identify these characteristics on slopes that have already avalanched. Then, as you are out in the backcountry, see if you can find slopes that have similar characteristics that haven't avalanched. These are exactly the types of slopes where you are most likely to encounter this problem today. The likelihood of encountering this problem isn't high, but the consequences sure are. 

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