Avalanche forecast

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

A complex and unstable snowpack brings dangerous avalanche conditions to our hills. You can trigger large avalanches that fail in surprising ways on most steep slopes today, from the valley bottoms to mountain tops. Slides will be larger and much more destructive as you gain elevation and move into wind-affected terrain. Skiers and riders triggered large to very large avalanches from hundreds of feet away on each of the past two days, and similar slides are likely again today. 

Avalanche problems

  • Persistent Slabs

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

    A series of recent storms built a thick slab of snow on top of a widespread weak layer. You are likely to trigger large avalanches involving this slab + weak layer combination today. In sheltered terrain, expect to find slabs that are 1-3 feet thick, and somewhat soft. In terrain that has been affected by the wind, you'll find 2-5 foot thick, very dense slabs. Avalanches that fail on this weak snow will break wide and fail in unusual locations. The layer of weak snow presents as surface hoar and/or facets on shaded slopes, and as a melt-freeze crust with facets on top on sunny slopes. 

    You can trigger avalanches involving this weak snow on most slopes, from the valley floors to the mountain tops. Pay attention to any steep slope with snow on it. As you gain elevation, the slides that you can trigger will become larger and more destructive. On Thursday, riders in the Beaver Creek drainage remotely triggered several very large avalanches from long distances away. One of these slides broke 800+ feet wide and was triggered from over a half mile away (see photo at right/above). I went to look at these slides yesterday and found that they had failed on a layer of surface hoar. I also remotely triggered several large to very large avalanches on the other side of the same ridge that failed on a melt-freeze crust with facets on top.

    Not enough weak snow for you? Further down in the snowpack, near the ground, another weak layer exists. Avalanches that step down to this layer of snow will send the entire season's snowpack rocketing downslope. Any avalanche involving the weak snow near the ground is likely to be unsurvivable. This basal weak layer (located at the base of the snowpack) exists on upper elevation slopes and shaded middle elevation slopes. 

    This photo shows several large avalanches that were remotely-triggered by riders in the Beaver Creek drainage. The furthest away slide is over 800 feet wide, and failed a half mile from where the avalanches were triggered, out of sight on the right side of the photo.

  • Wind Slabs

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

    The persistent slab problem described above exists on nearly all slopes. If you do choose to tiptoe your way through all of the low and middle elevation terrain that is threatened by this problem, you may encounter some avalanche issues that involve only the most recent snow. In exposed terrain, expect to find some relatively small wind slabs that may be sensitive to your weight. Loose snow sluffs can be triggered in areas where the snow surface has remained dry. If you're finding warm, moist snow at the surface you may be able to push some sluffs that have a wet character. Any of these smaller slides can trigger much larger avalanches as they travel downslope. 

Avalanche Discussion

UNIQUELY DANGEROUS CONDITIONS

You will encounter a complex, recently loaded, unstable snowpack capable of producing very large and surprising avalanches in the mountains today. If that doesn't give you pause, I'm not sure what will.

In the past 10 days, we've doubled our snowpack in many places, experienced a 36-hour long extreme wind event, watched temperatures flip between -40 F to 40 F, and weathered intense storms through 3 separate avalanche cycles. We have a uniquely bad weak layer in the middle of the snowpack that exists on nearly all slopes, and another widespread weak layer near the ground.  Riders and skiers have remotely triggered large to very large avalanches on each of the past two days. One of these slides was triggered from over a half mile away. Numerous avalanches have been observed at all elevations and all aspects, often occurring in places that don't frequently produce avalanches. 

So how do we manage this problem? Travel through the mountains knowing that you can make large avalanches in many locations. And that the type of slides you make will surprise you. You may find and trigger avalanches in places where you have never seen them before. Or you may see slides breaking much wider than you might expect. Head into the mountains expecting the unexpected today. Start with a conservative plan and stick with it. 

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