Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Wed
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

An intense winter storm bringing over a foot of snow and sustained wind is overloading a very weak snowpack. Avalanche danger will increase significantly throughout the day into the evening.  Human-triggered avalanches large enough to bury you will become almost certain, and very large natural avalanches are expected. Very large slides can run long distances to valley bottoms. Slides can be triggered from flat terrain a long distance away from a slope. Stay off of and out from under steep slopes. 

Avalanche problems

  • Wind Slabs

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

    Overnight we saw sustained strong winds that brought with them up to 8 inches of snow. This fell in addition to the over a foot of light snow that was already available for transport at upper elevations from our last storm. Wind drifted this snow into sensitive slabs both at upper and exposed middle elevation terrain. Expect these pockets to be reactive to your body weight and larger as you climb higher in elevation. As wind and snowfall continue throughout the day, expect the size and reactivity of these slabs to increase. In wind-sheltered middle elevation terrain, new snow is forming storm slabs that will be easy to trigger. 

    Importantly, these smaller slides can trigger much larger, much more dangerous avalanches on the persistent weak layer described above. Keep an eye out for rippled surfaces and hollow-sounding stiff snow. Cracks shooting out from under your feet is an indicator you have found a slab. The low-density snowfall will mask the presence of these slabs. Avoid drifts, dunes, and pillows.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–3

    Multiple large to very large persistent slab avalanches were remotely triggered in the Galena Summit and Eastern Mtns and Soldier and Wood River Valley zones three of the past four days (photo at right/above, video here). Slides occurred above Trail Creek, the East Fork of the Big Wood River, and near Baker Creek. These avalanches failed as dense, 2-3 foot thick slabs of snow. The culprit weak layer in these slides was the impressively widespread and fragile snow that developed during the December drought. Dig down and you'll find facets and/or surface hoar on shadier aspects and crust + facet combinations on sunnier slopes. 

    Triggering slides is very likely again today as we add more stress to the snowpack throughout the day. You can trigger avalanches that fail on these weak layers from long distances away from steeper slopes. Some of the triggered slides from the past four days released over 1,000' away. Pay attention to the terrain you are in, exposed to from above, and the presence of nearby parties. 

    The snowpack was touchy after it's first major loading event a few days ago — and now we're just adding to the stress on those same weak layers. The recent triggered slides clearly indicate that the snowpack is not reacting well to this loading. Pay attention to the terrain you are in and the terrain you are exposed to from above. 

    This large remotely-triggered persistent slab avalanche on a NE slope at 9400' above the East Fork of the Big Wood broke 250ft wide and ran over 1000' downslope.

Avalanche Discussion

A strong winter storm will build into the afternoon today, bringing up to 16 inches of new snow to favored locations by this evening over an incredibly unstable weak layer. Dangerous avalanche conditions already exist, and are going to get even more dangerous throughout the day today. By tomorrow morning, 1-2 feet of new snow will have fallen in the higher regions of this zone over a very weak snowpack that produced very large avalanches when it was loaded for the first time last week. This load will be much larger and sustained, making large to very large natural avalanches very likely.

Due to the widespread and impressively fragile nature of our weak layer in this zone, expect these slides to break in unexpected locations, and run bigger than you may have seen. Avalanches will be able to pull back into low angle terrain and are likely to be triggered from very long distances away. Ben and I were able to remotely trigger very large slides from up to almost a quarter mile away in this zone a couple of days ago. Today's avalanches will be larger and more destructive. There will be plenty of new snow near the surface that can form shallower slabs built by the wind in exposed locations, or form storm slabs in sheltered mid-elevation terrain that will be easy to trigger. These can be large enough to bury you on their own, however they also will be more than effective triggers to step down to the well-preserved persistent weak layer that forms the base of the snowpack. These persistent slab slides will move the entire snowpack downhill, making them our primary concern. 

We enter the mountains for different reasons. Some desire soft riding and skiing, some crave the challenge of moving through terrain, and others simply yearn to feel the joy of the mountain air. Regardless of your motivation, today we all should have the same goal on the forefront of our minds: come home safe. Staying off of and out from under steep slopes will be key to accomplishing this. Due to the likelihood of triggering slides from hundreds to thousands of feet away, we as backcountry travelers have a duty to each other to not only be mindful of the potential to trigger slides on other members of our party but other parties traveling near us. If you choose to head out today, keep in mind that we all have a common goal: walk back in that door tonight. 

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