Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You may be able to trigger avalanches large enough to bury a person at upper elevations and on some middle-elevation slopes facing W-N-E. You may or may not observe obvious warning signs like snowpack cracking or collapsing before triggering a slide. Avalanches are more likely in the snowier western half of this zone from Dollarhide Summit to the Soldiers and into the South Fk of the Boise River but are a concern anywhere you find enough snow to keep you off of the ground.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    You could trigger 1.5-2.5 foot thick avalanches that fail on buried persistent weak layers near the base of the snowpack. Weak layers exist on upper elevation slopes and most middle elevation slopes facing W-N-E. You'll find a stack of weak, sugary facets on shadier slopes and on sunnier slopes, a variable series of crusts and facets (photo). 

    You'll most likely find trouble where the slab above the weak layer is strong. The strength of the slab will vary from slope to slope. You've found a strong slab if pushing your ski pole to the ground is difficult. A strong slab will also likely support your weight if you hop off your machine or step out of your skis.

    You may or may not observe obvious signs of instability, like cracking and collapsing of the snowpack. Tracks on a slope are not indicators of stability—avalanches may be triggered after many riders have crossed a slope. The best way to manage this problem is to avoid avalanche terrain where stiff slabs rest above weak, older, facets and crusts. Short of that, you can reduce your risk by avoiding large avalanche paths and those with ugly consequences if you are caught in a slide.

Avalanche Discussion

Snow cover varies dramatically across this zone. This graphic shows the general increase in snow depth we've observed toward Dollarhide Summit and into the Soldier Mountains. More frequent and larger storms in these areas built a snowpack similar to those found further to the north. Regardless of which side of the zone you're in, if you're finding good coverage, you'll need to consider the persistent slab problem described above. 

The odds that you trigger an avalanche are low but not zero. The last known avalanche in this zone occurred an estimated two weeks ago on North Smoky Dome. It broke at least 500' wide and illustrates the destructive potential of a slide in the large, wind-loaded terrain of the Soldiers. While the weak layers involved in this slide have only marginally gained strength, the overall stability is improving as we've gone days without a significant storm.

Many soft snow surfaces exist, thanks only in part to recent snowfall. The prolonged drought has faceted the snowpack, even degrading once stiff, alpine drifts into soft, recycled powder. On the plus side, this faceting process has weakened the slab in some areas, limiting its ability to produce an avalanche. The downside is that strong snow over weak snow setups can be harder to identify, masked by softer snow at the surface. 

You'll find weak snow at the base of the snowpack at upper elevations and on most middle-elevation slopes facing W-N-E. These layers are widespread and exist across the forecast area. However, the recipe for a persistent slab avalanche calls for a slab. This key ingredient is found in fewer locations. Monitor the stiffness of the snow you're traveling through. Use your ski pole or hop off of your machine to feel for a strong slab beneath the surface. Stronger slabs are more common in our deeper snowpacks around Banner Summit, the Sawtooths, the W Smokys, and the Soldiers and on slopes that are wind-loaded. Areas that lack a slab can produce loose, dry facet-lanches. While less likely to bury you, these slides can easily knock you off your feet or carry you into unwanted terrain.

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