Avalanche forecast

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Sawtooth Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Dangerous avalanche conditions exist. Today's snow and wind could produce large, natural avalanches. Avalanches are most likely in windy, alpine terrain and on middle elevation slopes facing away from the sun. Slides may break wider than expected and can be triggered remotely—from gentler terrain above, below, or to the sides of steep slopes.

Avalanche problems

  • Wind Slabs

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

    Intense snowfall and wind are building sensitive drifts. These slabs will be thicker and more abundant as you climb into the alpine, where snow totals are greatest and the wind is strongest. Wind slab avalanches may release naturally and will be sensitive to your weight. Look for and avoid fresh dunes, drifts, and pillows that are commonly found near ridgelines and the sides of cross-loaded gullies. Cracking in stiff drifts (photo at right/below) indicates that you've found a sensitive slab. 

    (12/4/2023) Cracking in stiff drifts is a clear sign that the snowpack is unstable. This would have been an avalanche in steeper terrain. Galena Peak, Boulders.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2

    You're likely to trigger a persistent slab avalanche large enough to bury you. A layer of weak snow underlies a 1.5-2.5 foot thick slab on many upper elevation slopes and middle elevation slopes that face away from the sun. Today's storm is adding stress to this weak layer in both wind-loaded and sheltered terrain. 

    My guess is that you'll receive plenty of direct feedback, like cracking or collapsing of the snowpack, indicating that conditions are dangerous. You may even trigger avalanches remotely, from gentle, low-angle terrain as you ascend a safe ridge (video). In the absence of these obvious clues of instability, you can quickly and easily identify this layer by digging a quick hole. The weak facets will appear grey and feel loose and crumbly. On middle elevation slopes that face away from the sun, they may rest atop a stout ice crust, a particularly alarming and weak structure. 

    Many of you might be waiting for a bit more snow before you venture out, and I don't blame you, but it's time for all of us to get acquainted with this weak layer, as it's likely to stick around for a while. If you do head out, the only surefire way to avoid this problem is to steer clear of steep slopes where these old facets exist. 

Avalanche Discussion

A potent storm is causing the avalanche danger to peak in many areas this morning. Expect natural avalanches. Loose, dry sluffs will be common in very steep terrain. Some slab avalanches in wind-loaded areas may be surprisingly large and wide, spanning multiple terrain features. You'll find the most dangerous avalanche conditions on shadier, middle elevation slopes where the weak layers are at their worst, and in the alpine where the storm will build fresh, sensitive wind slabs. 

Last weekend's storm produced many natural slides in our snowier northern and western mountains. Some broke hundreds of feet wide and produced debris piles large enough to bury a person. Most observed slides failed in alpine wind-loaded locations, but avalanches were also observed in sheltered middle elevation terrain. While today's storm is not quite the relative thump as our last, it's still significant, and we should expect similar results (Titus video).

Today's a great day to keep it simple. The season is young, the snowpack is shallow, observations are limited, and we have a lot to learn. What we do know, is that the snowpack is generally weak where decent skiing exists, and it's shown its ability to produce large avalanches. I recommend that you keep your terrain choices conservative today, keep your slope angles low, and be alert to overhead hazard.

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