Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

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

To reduce the chance of triggering avalanches, avoid slopes where the wind recently formed drifts or slabs. In areas more protected from the wind, triggering avalanches is far less likely. Pay attention to the consequences of being caught in even small slides in terrain with rocks, cliffs, trees, and terrain traps.

Avalanche problems

  • Wind Slabs

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

    What is it? Expect to find isolated, hard wind slabs in exposed terrain. Sunday's storm brought a bit of new snow and a healthy dose of wind—especially to the Soldier Mountains—and today's expected strong to extreme winds could continue building slabs.Though not huge, these wind slabs could be sensitive to your weight and are adding weight to the buried weak layers described in Avalanche Problem 2. 

    Where is it?  You may find wind slabs near ridgelines, on the sides of gullies and chutes, and near prominent mid-slope terrain features. Wind slabs are larger and more widespread in the western half of this zone.

    How can you recognize it?  Cracks shooting out from your skis or sled are an obvious sign of instability. Watch for drifts, dunes, and ripples on the snow surface. Wind slabs can have a smooth, chalky appearance and feel and sound hollow, like a drum. Wind-deposited snow will be stiffer and keep your skis or snowmobile on or closer to the surface.       

    How can you manage it?  The easy move is to avoid obviously wind-loaded slopes steeper than about 35 degrees. Hard slab avalanches can behave unpredictably, breaking above skiers and riders. Small triggered wind slabs have the potential to entrain snow or "step-down" to buried persistent weak layers (Problem 2) lower on slopes, causing a larger destructive avalanche.  

    (1/30/2023) This large avalanche in the N Fork Soldier Ck drainage released on a SE aspect near 9000', likely over the Jan 28-29 weekend.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2

    What is it?  This zone has widely varying conditions as you travel from E to W: In the mountains above the Wood River Valley, recent dry weather has produced a snowpack that is weak and faceted but generally lacks a slab above the weaker snow. The important exception is wind-affected slopes where you find recent or past wind-loading. In the western portion of this zone, including Dollarhide Summit and the Soldier Mtns, conditions are more complex. Multiple weak layers exist. The most prominent is surface hoar buried 1-1.5 feet deep on some middle elevation, shady (W-N-E) slopes. While it's been over a week since the last reported persistent slab avalanche, triggering one is not out of the question on slopes over about 35 degrees in steepness with recent drifting or wind-blown snow.

    Where is it?  You're most likely to find trouble where the wind has loaded slopes or stiffened the snow surface. The buried surface hoar is most widespread in the western half of this zone in somewhat protected, middle-elevation terrain that faces W-N-E. Surface hoar is a tricky weak layer. It can be "spotty" in its distribution—it exists on some slopes, but not others.  

    How can you recognize it?   Wind-loaded slopes have harder surfaces and a distinct appearance (video to right/above). You may or may not experience snowpack collapsing and/or cracking while traveling. These red flags are obvious signs of instability. The layer of surface hoar is subtle and may not "jump out at you" when searching for it in a snowpit (see photo here).          

    How can you manage it?  You can reduce your risk by avoiding very steep (greater than about 35 degrees), shady slopes (facing W-N-E) with hard or stiff wind-blown snow at the surface—especially those with ugly consequences if you are caught in an avalanche. Persistent slab avalanches may break wider than expected or higher on the slope above you. 

    Note: In addition to the upper snowpack issues , older weak layers (crusts and/or facets, occasionally surface hoar) exist deeper in the snowpack. These are buried beneath dense slabs on some slopes. While triggering them is unlikely, it can't be ruled out in rocky, wind-affected, exposed terrain where the snowpack is less than about 3 feet thick. Ethan's video (right/above) shows you what to look for. 

Avalanche Discussion

While there are still some concerns about deeper weak layers—especially in the windswept, alpine reaches of the Pioneers, Boulders, and White Clouds—the limited recent avalanche activity occurred in the upper 1-2 feet of the snowpack.

If you've been following the forecast, you've read about a layer of surface hoar that was buried in early January. This layer was most reactive in the Sawtooths & W Smokys and Banner Summit zones that received the most snowfall, but triggered slides also occurred in the Soldiers and near Galena Summit. The most recent avalanche on the buried surface hoar released near Titus Ridge on January 29th (report). This layer is showing signs of improvement. However, surface hoar is an unpredictable weak layer; most of us aren't ready to write it off just yet, especially during a snowfall + wind-loading event.

Dry weather during the second half of January produced newer weak layers near the snow surface, ones that we're more familiar with:  facets and crust+facet combinations. Since January 27th, two smallish storms (both combined with wind) slowly loaded these newer weak layers, predominantly in our northern zones that received more snowfall. Early signs of instability such as cracking and poor snowpack test scores were observed last week in the Sawtooths, but there hasn't been quite enough snowfall yet to create a widespread problem. The current storm will continue to incrementally load these new weak layers, making isolated avalanches involving these layers possible.

While the danger is MODERATE and conditions aren't especially dangerous, there is enough complexity in the upper snowpack—primarily in the mountains north and west of the Wood River Valley—that it's worth using additional caution. Slopes over 35 degrees, especially those with recent wind loading, deserve respect. Before committing to riding or skiing in avalanche paths, spend a bit of time thinking about the consequences of triggering and being caught in a slide. Even small avalanches can cause big, bad outcomes on slopes with cliffs, trees, and terrain traps. 

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