Lawinenlagebericht

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Dangerous avalanche conditions exist,  especially in the western portion of this zone. Skiers triggered two avalanches yesterday on Galena Summit. Triggering an avalanche 16-24 inches thick is likely on wind-affected, upper elevation slopes. Avalanches are also possible in more sheltered terrain. Slides may be triggered from gentle terrain below, above, and to the sides of steep slopes. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Most observations yesterday came from the Galena Summit area, and they point to increasingly dangerous conditions on many slopes:

    • An experienced backcountry skier remotely triggered an avalanche on Titus Ridge while skiing an adjacent slope. He had arrived at the base of the slope when the avalanche reached him and buried him to his waist (more info).
    • A skier triggered and escaped a slide on Avalanche Peak (more info).
    • Several observers reported widespread collapsing of the snowpack.
    • I was in the White Clouds yesterday, where I found similarly unstable conditions (video, observation).

    Conditions are likely similar in the western portion of this zone, including the Soldier Mountains and the Dollarhide area. In these areas, small storms since mid-December have slowly (sloooowly!) loaded our nasty facet layer with a 16-20 inch thick slab. 

    Conditions are dangerous and scaling back our terrain choices—today, and into the future—is essential. You can significantly reduce the likelihood of triggering a slide by avoiding slopes steeper than 35 degrees, especially those that are exposed to the wind. Remote triggering is a real possibility—it's not just about the slope you're on, but also what's above and around you.

    Recent snowfall in the Wood River Valley has been less abundant, and the instability in the eastern portion of this zone is not as widespread. Pay particular attention to where the wind has built a thicker slab atop weak snow.

    (12/26/2020) An experienced backcountry skier apparently remotely triggered this avalanche on Titus Ridge while skiing an adjacent slope. He had arrived at the base of the slope when the avalanche reached him and buried him to his waist. Galena Summit & Eastern Mtns zone.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1

    On Bald Mountain, and especially in the Soldiers, weather stations reported increasing NW winds overnight. Combined with abundant soft snow, the wind may have formed small wind slabs in upper elevation terrain. These may be touchy on their own, but they are also adding more weight to the persistent slab problem discussed above.

Avalanche Discussion

GALENA SUMMIT & EASTERN MOUNTAINS, SOLDIERS & WOOD RIVER VALLEY:Each time we've loaded the fragile facet layer that formed during the early winter drought, many backcountry skiers and riders temporarily ratcheted back their terrain choices. But after a few days, folks are back to riding in steep terrain. In general, this approach has been appropriate—each of the small loading events hasn't quite been enough to produce widespread instability. Unstable slopes have remained relatively isolated.

I'm afraid that with the recent storm, we've crossed a point of no return. We saw more signs of instability—and triggered slides—yesterday than after previous loading events. In the true fashion of "persistent" weak layers, this instability is here to stay. Dangerous slopes have become more widespread, and identifying which slopes are unstable has become difficult. A more prolonged conservative approach will go a long way in keeping you out of harm's way moving forward.

SAWTOOTHS & WESTERN SMOKYS, BANNER SUMMIT:A persistent slab problem also exists in our northern zones, but it's a somewhat different beast. More significant loading since mid-December produced clear-cut, widespread instability. An impressive avalanche cycle occurred in these zones - you can see photos and read details in our new Avalanche Occurrence database. Yesterday's storm loaded the snowpack with a foot of new snow, and now the weak facet layer is buried well over 2 feet deep.

As the weak layer becomes more deeply buried, it results in the classic double-edged sword. Slides will be more difficult to trigger, but much more dangerous if one takes you for a ride. Signs of instability—like collapsing/cracking and poor snowpack test scores—may become less common. Over time, the weak layer is likely to heal under the weight of the overlying slab—but we're not there yet! As a result, a conservative approach to backcountry travel is just as important in our northern zones as it is further south.

Want to catch up on what's happened this past week? Be sure to watch our latest Weekend Update, published on Friday each week.

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