Lawinenlagebericht

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

You're more likely to trigger avalanches on wind-affected slopes with recently formed drifts or slabs. Consider the consequences of a slide before committing to avalanche terrain. Even small slides can be dangerous if they wash you into a gully, trees, or over cliffs. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2

    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 of slab of stronger snow. The important exception is wind-affected slopes where you find recent or past wind-loading. Pay close attention to the snow surface texture—watch for steep slopes where you find firmer or stiffer surface snow.

    In the western portion of this zone from Dollarhide Summit south to the Soldiers, a more complex situation exists with multiple weak layers in the upper few feet of the snowpack. The most prominent of these is buried surface hoar down 1-1.5 feet on many sheltered, shady (W-N-E) slopes. While it's been over a week since the last reported persistent slab avalanche, triggering one remains possible on some slopes—primarily on wind-affected slopes over about 35 degrees in steepness.

    In addition to the layers in the upper snowpack, older weak layers (crusts and/or facets, occasionally surface hoar) exist deeper in the snowpack. These are buried beneath dense, 2-4+ foot thick slabs. While triggering them is unlikely, it can't be ruled out in rocky, wind-affected, alpine terrain. 

    (1/30/2023) This 1-2 foot thick, skier-triggered avalanche failed on a layer of buried surface hoar. Surface hoar is frequently found in shady, partially treed locations like this. N-NE aspect near 9100' in the Salmon River drainage near Galena Summit.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Sunday's storm brought a bit of new snow and a healthy dose of wind—especially to the Soldier Mountains. Ridgetop winds eased yesterday but may have remained strong enough to continue to load some slopes. Be on the lookout for fresh wind slabs near ridgelines and on the sides of mid-slope features like gullies and ribs. Though likely to be small, these wind slabs could be sensitive to your weight and are adding weight to the buried weak layers described above.

    As you travel through the mountains, look for signs that the wind has been at work. Dunes, pillows, and ripples on the snow surface indicate that the wind has been transporting snow. Cracks shooting out from your skis or machine are a clear sign of an unstable slab.

    (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.

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—over the past month, most of the action has been happening in the upper few 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 where it was buried beneath more snowfall, but triggered slides occurred in the Soldiers and near Galena Summit. The most recent avalanche on the buried surface hoar occurred near Titus Ridge on January 29th (report). In most locations, this layer is showing signs of improvement. However, surface hoar is an unpredictable weak layer and most of us aren't ready to write it off just yet.

Dry weather during the second half of January produced newer weak layers, ones that we're more familiar with: near-surface facets, often near crusts. Since January 27th, two smallish storms (both combined with wind) have begun to slowly load these newer weak layers—especially 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. Another small storm is forecast for tonight—again favoring our northern mountains—which will continue to incrementally load these new weak layers. 

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. Spend a bit of time thinking about the consequences of triggering and being caught in an avalanche in the terrain you are in. Even small slides can have bad outcomes on slopes with cliffs, trees, and terrain traps. 

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