Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

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

Avalanches are most likely on slopes where the wind has built slabs on top of weak layers in the snowpack. Large avalanches failing on weak snow at the base of the snowpack continue to be a possibility. 

Conditions are more dangerous near the Smoky Mountain crest/Dollarhide Summit where the recent storm hit the hardest. Refer to the Galena Summit & Eastern Mtns Forecast if you're traveling in this area.

Avalanche problems

  • Wind Slabs

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

    Last week's storm dropped 12-30" of new snow in this zone, accompanied by strong winds. The greatest amounts fell from Dollarhide Summit SW towards the Soldiers. Despite lower snow totals around the Wood River Valley, small, natural, and skier-triggered avalanches were reported this past week, and a fresh natural wind slab was reported yesterday (photo above/right). Wind slabs will be most common at upper elevations, but this week's wind also drifted some open middle and lower elevation terrain (example).

    These slabs have had a bit of time to bond to the surfaces that they were deposited on but there are still places where you can trigger them. In this zone, these wind slabs are most concerning where they overlap with the persistent slab problems described below. Stiff slabs on top of weak layers (those in the middle of the snowpack as well as at the base) are never a good combination. 

    ADDITIONAL DISCUSSION A crust+facet combination exists underneath last week's storm snow on slopes that directly face the sun (southern half of the compass). This layer produced a number of large, natural avalanches in neighboring zones during the recent storm:

    •  SW Bowl of Galena Peak (photo)
    • In the Boulders near Mushroom Ridge
    • Behind Horton Peak in the Pole Creek drainage (photo).

    Time will tell how long this layer will be problematic, but I'll be particularly leery of slopes where this layer exists for the next bit.

    (1/8/2022) Small natural wind slab avalanche in Croy Canyon. 6800’, E. Photo: V. Rossin

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Weak October snow is buried 2-5+' deep on most shady middle and upper elevation slopes. Some sunnier, upper elevation aspects have this layer too. The recent storm event just added a huge load to this weak layer, especially on wind-loaded slopes. It is the most deeply buried near Dollarhide Summit SW to the Soldiers. The recent storm largely missed the mountains above the Wood River Valley, but avalanches observed earlier this season indicate that this weak snow is problematic where it exists. 

    This weekend's observations in neighboring zones revealed surprisingly few avalanches breaking deep into the October snow (although see photo above/right), which offers some hope for a future where we're less concerned about this layer. But I don't think we're quite there yet. Where are you more likely to trigger an avalanche on this layer? Most savvy backcountry skiers and riders are still avoiding very steep (>35 degrees), rocky, wind-affected slopes at upper elevations and in alpine terrain.

    (1/8/2022) Natural avalanche near Titus Ridge in the Galena Summit 7 Eastern Mtns zone. Judging by the depth, it looks to have failed on weak October snow near the ground. 9400', N. Photo: T. Haskins

Avalanche Discussion

LIFE CYCLE OF A WEAK LAYER Here at the Avalanche Center, we spend a lot of time thinking about weak layers. We live in a snow climate that is particularly good at generating layers of weak snow that linger for days and weeks. These layers don't just spontaneously appear in the snowpack, they are created when the snow is still at the surface, exposed to the environment, and then get buried by subsequent snowfall. Right now, we are dealing with a few different weak layers in the snowpack; one that has been buried for over a month and another that has been buried for just a few days. Across our region, there is a lot of variability in both the nature of these weak layers and the character of the slab overlying them. 

I'm sure that you are well aware of the layer of "October snow" that exists at the base of the snowpack. This layer has been responsible for dozens and dozens of avalanches that we've observed in the past month. We've had the benefit of a few storms worth of data to watch how this snow has behaved during loading events and dozens of field days looking at it up close. The new player in the weak layer game, which we started to bury on January 3rd, is a different story. We know this layer can produce avalanches because we've already seen a handful of them. But we don't know how it will behave going forward. 

In my personal backcountry travels, I like to take a step back when I have a high degree of uncertainty, and that is how I'm dealing with this weak layer for now. We have a good sense that it is most problematic on steep slopes that face the sun directly, where it exists as a layer of facets adjacent to a crust. Because of that, I have taken this type of terrain off my personal backcountry "menu". I'm also planning to focus much of my attention on this layer in the coming days in order to get a better sense of where it is at its worst and how it is changing over time. I'll head out the door with a hypothesis in my head, compare that to the observations that I make in the field, and update my mental model accordingly. Expectations, observations, repeat.

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