Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You could trigger a 1-3 foot thick avalanche on slopes that are exposed to the wind. To significantly reduce your odds of triggering a slide, steer clear of steep terrain with evidence of recent wind loading such as cornices, pillows, and drifted snow. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Yesterday, skiers near Baker Ck found small, sensitive drifts in middle-elevation terrain. These slabs will be thicker and more abundant as you climb into windier, alpine terrain. Look for evidence of fresh windblown snow such as drifts, pillows, and new cornice growth. Slabs commonly form just downwind of ridgelines or on the sides of cross-loaded gullies. While I'd expect these slabs to be relatively small, they are likely to be sensitive to your weight. 

    Cracking, or collapsing of the snowpack are clear signs that you've found unstable snow. Given the increased chances of triggering both a wind slab and a large persistent slab avalanche on wind-loaded slopes, the prudent move is to avoid obviously wind-loaded avalanche terrain.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    A variety of weak layers exist in the upper 3' of the snowpack. They appear to be most problematic on middle and upper elevation sunny slopes where they exist as a crust+facet combination. These layers also exist on shadier aspects where an obvious crust may not be present and where we're occasionally finding surface hoar (photo). 

    The exact location, makeup, and sensitivity of these layers vary and are difficult to pin down. The complexity and spatial variability of this problem make slope scale stability assessment a highly uncertain task. The safest bet is to assume one or more of these layers exist and are capable of producing a large avalanche. 

    These layers are slowly healing. Slopes steeper than about 35 degrees, and/or those with recent wind loading will take the longest to stabilize. Therefore, avoiding steep, wind-drifted terrain is an effective way to reduce your odds of triggering a large avalanche. 

    ADDITIONAL DISCUSSION: While triggering slides on faceted snow deep in the snowpack is unlikely, it can't be ruled out in steep, rocky, wind-affected alpine terrain. Slopes like these have variable snow depths, and thinner snowpack areas allow our weight to more easily impact deeply buried weak layers.

    (12/31/2022) This large avalanche was remotely triggered from hundreds of feet away on 12/31. It failed on a S-facing slope at 9,500' near Mushroom Ridge, which is near Galena Summit.

Avalanche Discussion

Today's fair weather won't affect the avalanche danger. The persistent weak layers in the upper 3' of the snowpack are slowly healing, but as the name "persistent" implies, the overall picture today is much the same as yesterday. Stability is improving, but as Chris pointed out yesterday, "conditions are still ripe for getting surprised". Why? The complex distribution of weak snow in our upper snowpack means stability could change dramatically from slope to slope. Today, you likely won't observe any obvious "red flag" warning signs that conditions are dangerous. When the danger is not "in your face" it can make choosing a safe place to play a much harder task. This is especially the case when we're dealing with overlapping and sporadically distributed persistent weak layers. 

Today, the complexity of the snowpack and therefore my terrain selection remains the same. When faced with uncertainty in the backcountry, choosing safer terrain is the only way to reliably reduce your risk. That means ruling out steep, upper elevation, wind-loaded slopes—a message we've hammered home over the last week, and one remains the best advice again today.

Be sure to check out JP's Weekend Update for a recap of the recent natural and human-triggered avalanches over the past week.

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