Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

You could trigger a 1-3 foot thick slab avalanche on very steep, wind-affected slopes. These slides are most likely at upper elevations where recent strong wind formed stiff drifts. To reduce your risk, steer clear of obviously wind-loaded terrain where the snow surface is hard.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    The Soldier & Wood River Valley zone has been "spared" the recent snowfall that's fallen further north, but who needs snow when you have wind? Extreme wind events this past week “repurposed” snow from windward slopes and deposited it into thick, hard, wind slabs. In many areas, these 1-3 foot thick slabs sit atop weak, sugary facets in the lower portions of the snowpack.

    Triggering a slide on one of these weak layers is unlikely. However, if you were on a mission to find one, here's where I would look: exposed, wind-loaded terrain steeper than about 35 degrees, including cross-loaded gullies lower on slopes.

    If the snow surface is hard or you see cracks shooting out from your skis or sled, it's time to pay attention. Picture where an avalanche could carry you before committing to skiing or riding exposed avalanche terrain—the consequences of a triggering a powerful persistent slab should not be taken lightly.

    ADDITIONAL DISCUSSIONIf you’re traveling along the northern boundary of this zone including areas near Dollarhide Summit and Skeleton Creek, refer to the wind slab discussion here.

Avalanche Discussion

The wind is probably one of our least favorite winter weather factors, second only to the "r" word. But since last Monday, it has been the primary force behind our avalanche conditions. As you likely know, when the wind is sufficiently strong, it picks up snow from one spot and puts it in another. While the snow particles blow through the air or bounce along the snow surface, they break up and become smaller. The smaller snow grains more easily pack into dense, stiff, or even hard wind drifts once they're deposited. And—ta-da—you have a wind slab.

In areas where these wind slabs form atop snow surfaces that aren't persistent weak layers, such as softer new snow, older wind slabs, and crusts, the period of instability is often short-lived. Warmer temperatures can help to speed up the process of stabilization. The trouble is that consistent winds over the past several days formed fresh, touchy wind slabs even as old wind slabs stabilized. With any luck, today will be the last day of the persistent winds and wind slabs will get a chance to heal once and for all.

The more complex issue with the recent wind loading is where the wind slabs are adding additional weight to buried persistent weak layers. Where our snowpack remains shallow and especially weak—for example the windswept Boulders and the Wood River Valley—the recent wind loading kicked off a round of natural and triggered avalanches. This problem is likely to persist longer than the "pure" wind slab problem and has the ability to produce a much larger avalanche.

Fortunately, areas with recent wind loading are easy to identify with "look and feel"-type observations. The snow surface on wind-affected slopes usually has a different texture and will be denser and more cohesive than the snow found on sheltered slopes. Pillows and dunes indicate areas where the wind has deposited and drifted the blowing snow. Keeping your eyes open for these clues, and avoiding steep slopes where you find them, will help you avoid most of the avalanche risk that currently exists in our area. This is especially true if you find yourself in alpine areas or where the snowpack remains on the shallow side.

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