Bollettino valanghe

Sawtooth & Western Smoky Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Your main avalanche concerns involve the new snow from the past week. Be on the lookout for sensitive pockets of wind-drifted snow near ridgelines; cracking in these drifts is an indication of instability. Small loose snow avalanches will be easy to trigger on very steep slopes. These may occur naturally where the sun is melting the snow surface.  Triggering large avalanches that fail on deeper weak layers is unlikely, but the consequences would be grave. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Be on the lookout for freshly formed wind slabs in your travels today. Surface textures like dunes and drifts indicate the wind has been at work. If the snow you are moving through quickly becomes deeper, stiffer, and more dense, you have found a wind slab. Cracks shooting out from your skis or machine are a clear sign that the slab you found is not well bonded.

    Look for these slabs near terrain features that slow the wind down and force it to drop the snow it is transporting. Typical locations are along ridgelines and the sides of mid-slope gullies. Slabs will be at their largest, most reactive, and most dangerous in upper elevation terrain. Even small slabs can knock you off your feet and send you for a nasty ride if you encounter them in ugly terrain. Consider the consequences of an unplanned, high-speed trip down the slope you are playing on. 

    ADDITIONAL DISCUSSION: Loose snow avalanches involving the recent snow will be small but easy to trigger on steep slopes. These will run quickly downslope on the stiff surfaces underneath. As periods of bright spring sunshine melt the new snow, these loose snow slides will take on a moist/wet character. These types of slides can entrain a lot of debris in the steep, rocky, confined terrain that is typical in the Sawtooths. These types of slides were releasing naturally in the sun yesterday and may continue to do so today. 

    (3/28/2024) This 12-16" thick wind slab was ski cut on a small wind-loaded slope in the Smiley Ck drainage (8700', N). Photo: Sawtooth Avalanche Center

Avalanche Discussion

Your primary avalanche concerns today involve the 10-20 inches of snow that fell over the past week. Roughly half of this fell last weekend, with the other half falling on Thursday. Stiff, icy crusts underlie this recent snow on slopes that tilt towards the sun. Expect to find some relatively small wind slabs that remain sensitive to your weight today. Most of these slabs aren't likely to be large enough to bury you, the main hazard they present will be if they knock you off your feet or machine in unfriendly terrain.

Triggering very large avalanches on deeper weak layers has become unlikely in this zone. Unlikely, but not impossible.  The most recently triggered large slab avalanche that failed on buried persistent weak layers in this zone occurred in the Sawtooths on March 14th. The slide failed in a steep, north-facing couloir on Williams Peak (photo here). You'd have to get unlucky to trigger one of these beasts, but it would take an equal dose of good luck to survive unscathed.

As the danger gradually decreases, many of us find ourselves drawn towards bigger, steeper, more complex terrain. When we head into this terrain, we enter a dangerous environment, even when the avalanche conditions are generally safe. Catching an edge, crossing your ski tips, or losing control of your machine on a steep, firm slope can all have severe consequences. This is also the type of terrain where you are most likely to trigger a slide that can knock you off your feet. If this is the type of terrain you are headed for today, remember to keep things tight. Travel one at a time, keep your eyes on your partners, and make a plan for how to move safely through the terrain. Respect the environment you are traveling through and remember that avalanches are only one of the hazards posed by the mountains.  

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