Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

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

Conditions are dangerous at upper elevations. Expect to trigger large, 1-3 foot thick avalanches where the wind has drifted snow or stiffened the snow surface. Similar slides are possible in terrain more sheltered from the wind—especially in the Soldiers and in the mountains surrounding Dollarhide Summit.

 

Avalanche problems

  • Wind Slabs

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

    Expect to find sensitive slabs in both obviously wind-loaded and more sheltered terrain. Monday in the western Smokys, a snowmobiler remotely triggered a slab avalanche that released in wind-loaded terrain below a cliff. You could trigger similar avalanches today.

    Yesterday's blowing and drifting snow continued to build sensitive slabs. Triggered slides will be thicker, wider, and more dangerous at windier, upper elevations. Look for them near ridgelines and along mid-slope terrain features like ribs and gullies. Stiff slabs may extend into wind-exposed middle elevation terrain (photo, photo). Some wind slabs formed over weak snow (facets, surface hoar, crusts), which may make them more sensitive to triggering and could cause them to break wider than expected.

    Snowpack collapsing or cracks shooting from your skis or sled are obvious signs of instability. Ample low density snowfall and shifting wind may mask the usual clues that the wind has been at work. This may make it difficult to identify a recently wind loaded slope from a distance. Even subtle wind affect over the past ten days may be enough to stiffen the snow and increase your odds of triggering a slide.

    ADDITIONAL DISCUSSION: Multiple layers of weak snow exist in the upper 1.5-2.5 feet of the snowpack. Continued snowfall is building a thicker, stiffer slab above these layers, pushing some of them to their breaking point. While most dangerous in wind-loaded terrain, you could also trigger a large slab avalanche involving this weak snow in areas that are protected from the wind. This scenario is most likely in the Soldiers and in the mountains surrounding Dollarhide Summit. See the forecast discussion for details. Wind slab avalanches, cornice breaks, or sluffs can act as triggers stepping down to these weak layers to produce a very dangerous slide. 

    (2/28/2023)

    This fresh wind drift was triggered from a distance. Expect to find sensitive slabs in areas exposed to the wind. Snowpack collapsing or cracks shooting out from your skis or sled are obvious signs of instability. Galena Summit, Photo: P. Graham

Avalanche Discussion

Steering clear of wind-loaded avalanche terrain is the best way to reduce your risk of triggering a large avalanche, but it's far from the whole story. Wind-loaded slopes harbor recently formed drifts and slabs. These slabs will be dangerous in their own right, thanks to the combination of several inches of new snow, wind, and the weak layers on which they formed, but they also add weight to a host of weak layers in the upper 3' of the snowpack. So far, the majority of the slides we've seen have initiated in wind-loaded terrain, but this is starting to change. Slabs of snow are beginning to overwhelm weak layers in terrain that lacks an obvious wind load. 

We added a persistent slab problem in the Sawtooth and Western Smoky Zone yesterday. This zone has received the most recent snow and has the thickest slab. The Banner Summit Zone is not far behind and I added a persistent slab problem there this morning. Honorable mentions go out to the White Clouds, Smokys, Soldiers, and the mountains surrounding Galena Summit and Dollarhide Summit. These areas may be slightly behind, but not by much. 

While wind-loaded slopes are obviously dangerous today, identifying the wind-loaded slope from a distance could be challenging. If you are planning to head to any of the abovementioned areas, know that it may no longer require an obvious wind load to be dangerous. Many slopes may be teetering on the edge. Today is a good day to choose conservative terrain, keep your slope angles low, and anticipate the possibility of triggering a slide from below, above, or to the sides of a steep slope. Let's take a step back today and see how it all shakes out.

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