Lawinenlagebericht

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Sawtooth Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Avalanches are most likely in areas where the wind has formed drifts or stiffened the snow surface. Triggering avalanches in areas that appear to be sheltered from the wind is not out of the question. You could trigger slides remotely—from flat terrain below, above, and to the sides of steep slopes.

Saturday, snowmobilers triggered a large avalanche from below in the Salmon River headwaters. One rider was caught, carried, fully buried, and successfully recovered. Read the Forecast Discussion for preliminary details. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    What and where is it: You are most likely to trigger a large, thick, 2-5 foot thick avalanche in terrain where the wind frequently blows and the snowpack depth is variable. Triggering an avalanche is much less likely—but not out of the question—on steep slopes that appear to be completely sheltered from the wind. The slabs rest above a variety of weak layers (facets, surface hoar, crusts, and combinations) on most slopes.

    How can you recognize it: Watch for cornices, snow pillows, dunes, and ripples (photo). Feel for stiff snow under your feet or sled. These are signs the wind has been at work transporting snow. Slopes with rocks poking out of the snow have variable snow depths, making it easier for you find a spot to impact the buried weak layers that exist on most slopes.    

    How can you manage it: Before triggering an avalanche, you may or may not experience obvious signs of instability like snowpack cracking (photo) and collapsing or whumpfing. Avoid obvious wind-loaded slopes and terrain that is peppered with rocks sticking out of the snow. Persistent Slabs can release in surprising ways, break wider than expected, and release above or hundreds of feet away from where they are triggered. We can't assume tracks on a slope mean it is safe; several people could descend a slope before triggering an avalanche. Remotely triggering an avalanche from flat terrain near steep slopes is a real possibility. Pay attention to how steep the terrain above you is. 

    Additional Discussion: You may be able to trigger thinner wind slab avalanches that formed near ridgelines and in cross-loaded areas on the sides of gullies. The size and chance of triggering these slides increase significantly as you climb into windier, alpine terrain at upper elevations. These avalanches could step down to the buried weak layers described above.

    (1/4/2025) Snowmobilers remotely triggered this very large avalanche in the Salmon River headwaters. One rider was caught, fully buried, and successfully rescued. The crown is on a NE aspect near 9300'.

Avalanche Discussion

Yesterday, a group in the Frenchman Ck drainage reported remotely triggering an avalanche (2-3 feet thick, near 9000' on a NW-W aspect) while skiing in safe, gentle terrain nearby. The slide appeared to release in a wind-affected clearing a couple hundred feet below a lightly corniced, treed ridgeline. 

On Saturday, Jan 4th,  snowmobilers in the Salmon River headwaters remotely-triggered a very large avalanche from several hundred feet below where the avalanche originated. The resulting slide caught, carried, and fully buried one of the riders. The rider deployed his airbag and was carried through trees. The other riders located the buried rider and extricated him from the debris in approximately 15 minutes. He was alert when he was evacuated to a local hospital for evaluation. The avalanche occurred on a NE aspect near 9500’ in elevation, was about 900 feet wide, and averaged 4 feet thick. 

These recent events highlight a pattern: slopes near and above about 8500' that face NW-N-NE-E-SE are the most concerning. We've seen the most recent avalanche activity in this terrain, and there you'll have the best chance of finding the combination of stiff, wind-affected snow and buried weak layers.

The odds of triggering an avalanche are decreasing, you may not see any signs of instability, snowpack test results could look OK, but the consequences of triggering a slide remain severe. In recent days, several experienced observers reported not seeing any signs of instability but continuing to avoid avalanche terrain. One group summed it up nicely, calling the Persistent Slab probem "spooky."

Conditions are tricky. If you want to take triggering avalanches off the table, the only surefire strategy is to avoid avalanche terrain entirely. If you're willing to accept more risk, avoid areas with wind-affected snow. Avoiding large avalanche paths and those with terrain traps (creeks, trees, or gullies where you would be carried or buried) will always stack the odds in your favor. 

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