Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

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

Triggering a large avalanche is unlikely.  Unstable slopes are becoming few and far between, but triggering a 1-3 foot thick avalanche may be possible on very steep, wind-affected slopes. You could trigger smaller avalanches where the wind has recently formed 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

    Monday's strong NE wind event transported enough snow to maintain the threat of triggering a 1-3 foot thick persistent slab avalanche. In the Boulder Mtns (Galena Summit & Eastern Mountains zone), several 2-3 foot thick slides released naturally on W aspects with thin snowpacks. The slopes that failed are usually wind-scoured; you might find similar snowpack setups in isolated, exposed terrain in this zone. The weak layers we've struggled with all winter got a breather for much of the past couple weeks, but the recent wind-loading is stressing the thin, weak snowpack on some slopes.

    Are you likely to trigger a big slide on weak layers in the lower part of the snowpack? No.  But, if you were on a mission to hunt down one of these elusive persistent slabs, 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,1-3 foot thick, persistent slab should not be taken lightly.

    ADDITIONAL DISCUSSIONWhile today’s snowfall will favor our northern zones, there is some uncertainty in how far south the snow will push. Wind is already cranking out of the NW and all we need is a little shot of snow to build small sensitive wind slabs. This scenario is more likely in the Soldiers than the Wood River Valley. These slabs will add to those created during Monday’s wind event.

Avalanche Discussion

There are two avalanche problems to contend with today: freshly forming wind slabs at the snow surface and persistent slabs that have the potential to break on weak layers in the lower half of the snowpack. 

Today’s storm will favor our northern mountains where more than a foot of new snow is possible by mid-morning tomorrow. The hazard posed by new snow and wind is relatively straight-forward. Fresh drifts will be sensitive to your weight, and if you’re out today, the snow stinging your face will be a good reminder to keep wind slabs at the top of your mind. It looks like the spike in the avalanche danger will likely occur later this evening as snowfall rates increase and a jet streak bumps up the wind speed from the NW and W. 

Less obvious are the hazards that lurk below. The weight of new-fallen and wind-blown snow will stress weak layers deeper in the snowpack. Over the weekend and earlier this week, these layers proved they weren’t quite ready to go away quietly. Persistent slab avalanches were observed in the White Clouds, the Boulders, and the Pioneer Mountains. Similar avalanches are possible again today, particularly in areas where storm snow overloads a shallow weak snowpack.

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