Avalanche forecast

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The weight of recent snow is stressing the snowpack. You're likely to trigger large, destructive avalanches—especially in steep, recently wind-drifted terrain. Avalanches may be triggered remotely—from below, above, and to the sides of steep slopes.

Avalanche problems

  • Persistent Slabs

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

    This zone picked up around 0.5-1" of SWE since Tuesday afternoon. This load was enough to release large slab avalanches in the Boulder Mountains and cause a widespread avalanche cycle in the Smokys. Avalanches occurred on many different aspects, in both obviously wind-loaded and generally sheltered terrain. 

    A weak layer of sugary facets buried in mid-December is responsible for the vast majority of natural and human-triggered avalanches so far this season. If we've learned anything from previous storms, it's that this weak layer doesn't like to be poked and it can remain irritable for days following a storm. A spate of human-triggered avalanches followed each of our last two storms and we should expect human-triggered avalanches to be likely again today. 

    Remotely triggering slides from below, above, and to the sides of steep slopes is likely—particularly where you find stiff, freshly formed wind slabs near the surface.

    (1/11/2021) Very large persistent slab avalanche on the headwall at the back of Lake Creek. Crown is at least 1000' wide. Based on earlier observations it likely failed between 1/10 and 1/11. Expect more of this type of activity with this storm.

  • Wind Slabs

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

    Yesterday's strong to extreme SW-W-NW wind rapidly built fresh wind slabs. Expect to find both hard and soft slabs in many locations. These slabs will be thicker and more widespread at upper elevation, but touchy wind slabs may exist in exposed terrain at any elevation. Cracks shooting from your boards or sled are the best indication that you've found a sensitive slab. Wind slab avalanches that release near ridgelines could "step down", failing on layers deeper in the snowpack and becoming much wider than the initial avalanche. 

    (1/13/2021) A large slab avalanche in the Boulder Mountains on Cabin Peak (near Galena Peak).

Avalanche Discussion

The predominant weather pattern this winter has heavily favored the western portions of this zone from the Smoky Crest near Dollarhide over to the Soldier Mountains. The snow depths in these areas are 1.5-2 times greater than those near Baldy. It's important to note that differences in problem distribution and avalanche hazard exist within each zone on any given day. A relatively thin snowpack in the mountains surrounding the Wood River Valley is in stark contrast to areas further west. As Scott pointed out yesterday, "we try to provide as much information as possible each morning, but it’s important to recognize that the Forecast products cover large areas; they are designed to serve as a starting point, and you get to make the ultimate decisions about how and where to play." 

Tuesday and Wednesday's storm dropped anywhere from 0.5-1.5" of SWE. For storm totals across the forecast area, check here. Although precipitation diminished early in the day yesterday, strong to extreme W and NW wind continued to load slopes at all elevations. As one observer stated, "we were looking up into the Boulders all day watching active wind transport and expecting naturals to release".  I shared the same thoughts as I walked out Titus Ridge near Galena Summit. You can see a short clip of active wind-loading here. 

The uncharacteristically weak nature of the facets in the lower third of the snowpack has produced widespread natural avalanche cycles with relatively light loads. This last storm, while not huge, again tipped the scales. Continued wind-loading for several hours following the storm has only added to the problem. Yesterday, as I looked south along the Smoky Crest nearly every steep slope between Titus Lake and Titus Peak had avalanched. Ben spotted numerous, meaty slab avalanches in the Sawtooths (photo, photo, photo). Large avalanches were also spotted in the Boulders. This of course is only a partial list. We didn't get a good look at the Soldiers, or mountains near Banner Summit but given the track record of this weak layer, it's not going out on a limb to expect to see evidence of natural activity there as well. 

The lure of fresh snow and mild weather over the next few days will be strong. Trust me, I get that, but I urge you to build an extra safety margin into your travel plans. The weak layer we're dealing with is special, but I hesitate to call it "unpredictable". We've seen what it can do, and we know it can be touchy for days after a loading event. Don't lose sight of those facts as you choose where to ride this weekend. 

 

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