Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
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Out of date — this forecast expired 7 years ago.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

It remains possible to trigger an avalanche on slopes with wind-stiffened or drifted snow. Although buried weak layers are improving, lingering signs of instability indicate we're not out of the woods yet. Avoiding steep slopes with evidence of wind drifting continues to be the best approach.

Avalanche problems

  • Persistent Slabs

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

    By now, you've heard plenty about the layer of surface hoar buried 1-2 feet deep throughout our area (read more about it in the Forecast Discussion below). It was responsible for human-triggered avalanches in the Soldiers last weekend. Although this zone received less recent snowfall then our zones to the north, it still remains possible to trigger an avalanche in areas where recent or past winds have drifted snow.

    Wind-loaded slopes are more common near the Smoky Crest around Dollarhide Summit and in the Soldiers than in the mountains surrounding the Wood River Valley, so the chances of finding trouble increase as you move west in this zone. Friday in the Soldiers, Scott found that wind-affected slopes remained sensitive during snowpack tests (see video). Observations like these indicate it's still possible to trigger an avalanche, and avoiding steep slopes with evidence of wind drifting continues to be the best approach.

Avalanche Discussion

As many of you know, surface hoar is essentially the equivalent of frozen dew. Clear, cold nights will cause moisture in the air to freeze onto the snow surface, forming delicate frost feathers. Once formed, surface hoar is very fragile and can melt or blow away before it gets covered by new snow. 

On December 7th, the right combination of conditions conspired to not only form surface hoar uniformly across our area, but also to bury it before it was destroyed. While our area is known for some wicked facet layers, a widespread surface hoar layer isn't particularly common. Sure we get them occasionally, but they tend to be more "pockety" in nature and rarely produce such impressive avalanche activity as the one we have now. Surface hoar can be extra tricky—in fact, some studies have shown that it's the weak layer that produces the most avalanches that catch professionals. 

So while we may not be happy to have this layer beneath our skis, board, or machine, it does present a unique opportunity for those that are curious about snow. Surface hoar is often difficult to identify in snow pits, but that is not the case right now—you'll almost certainly find an obvious horizontal stripe about 1-2 feet beneath the snow surface. Perform a snowpack test or two and see how the layer responds. Even if your tests don't give results, just seeing the layer there will likely give you pause.

So don't just take our word for it, dig down and see it for yourself. You may find that getting your eyes on the surface hoar layer makes it easier to be extra cautious in your terrain choices. As they say, seeing is believing.

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