Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Alta quota
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Limite del bosco
2 · Moderato
Sotto il limite
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In sintesi

Triggering a large avalanche that breaks widely on buried weak layers is your primary concern today. The likelihood of this is gradually decreasing, but it remains a worrisome possibility. Slides can be triggered from long distances away. Don't expect obvious signs of instability before triggering an unsurvivable slide. Wet loose avalanches will release naturally on steep, rocky slopes during the heat of the day as the bright March sun melts the icy crust at the snow surface.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Widespread layers of weak snow can produce large avalanches here. These are buried beneath dense, 1-5 plus foot thick slabs, which makes triggering slides more difficult. These thick slabs also mean that any slide you trigger will be large and destructive. Skiers triggered at least 3 large avalanches in this zone in the past week. Do not expect feedback to receive obvious feedback from the snowpack today. The first sign of instability may be the large, wide avalanche that you trigger. These slides can be triggered after dozens of skiers or riders have traversed a slope. Triggered slides are likely to break far above you, making escape difficult to impossible. 

    Avalanche activity during major storms of the past two weeks was widespread, occurring on all aspects. Many huge slides in this zone failed on persistent weak layers in the upper and middle portion of the snowpack. You'll find a variety of weak layers here (crusts with facets on solar slopes, and facets without crusts on shaded slopes). These weak layers have gained some strength and the likelihood of triggering a slide on them is gradually decreasing, but the consequences would be severe.

    Triggering a slide is most likely in steep, rocky, open, heavily wind-affected terrain (photo at right/above). You can reduce your risk by avoiding this type of terrain. 

    (3/7/2024) This large avalanche was triggered remotely from the ridge. It released in a heavily wind-loaded gully on a weak layer of snow buried at the end of February. Croy Creek, NW @ 6,000'.

     

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–1.5

    Temperatures are starting 5-15 degrees F warmer than yesterday. However, today's wind and cloud cover may keep wet loose problems at bay. It will be fairly apparent if you need to be worrying about wet snow issues today or not. If surface crusts are breaking down and the snow you are moving through is becoming wet, or if you are traveling under large, rocky, sun-soaked slopes, consider the possibility of wet snow avalanches. Temperatures may become warm enough at lower elevations to melt the snow on shaded slopes. 

    These slides start at a point and fan out as they travel downslope and gather speed and debris. Pay attention to the terrain above you and the consequences of being knocked off your feet and sent downhill by one of these slides.

    (3/6/2024) Loose snow avalanches caused by warming from the sun. Photo: Sun Valley Heli Ski

Avalanche Discussion

FAILURE OF IMAGINATION

Yesterday, a group of skiers in the Baker Creek drainage triggered an enormous collapse that traveled over 1,500 feet, shattering the snowpack across a broad area. The skiers were on their third lap up their skin track when they felt the slope collapse and watched fractures spider-web the snow in front of them. They had not experienced any signs of instability, and their snowpack tests did not return unstable snowpack test scores. On a steeper slope, this collapse would have triggered a massive avalanche, the sort that snaps green timber like toothpicks and leaves a pile of debris that doesn't melt until July. This is a perfect illustration of the world that you will be moving through today.

Imagine trying to wake up a sleeping elephant with a feather. The thick, leathery skin of the elephant makes it tough to get the message across, but if you find a thin spot in the beast's armor you will quickly find yourself questioning your life choices. Our snowpack is similar. You'll move around on the surface, enjoying the soft snow, dodging the crusts, and smiling at your friends. There won't be many or any indications that there are layers of weak snow underneath the thick slabs at the surface. And, more likely than not, you won't trigger a massive avalanche. But if you do... 

MODERATE Avalanche Danger with widespread persistent slab instabilities is serious business. The mountains aren't likely to give you obvious signs of instability today so you will need to spend some time exercising your imagination. Look up at big pieces of avalanche terrain and try to visualize the layers of weak snow that lurk in the snowpack. Picture what your terrain would look like with a stark, sharp crown wrapping around the entire slope. Look at the terrain below your slope and picture a pile of debris that would erase your house.  Imagine the awful feeling of realizing your friend is under there.

Enjoy the sun and our snow-covered mountains, but think about the sleeping elephants when you're out there. Be honest with yourself about the games you are playing, the risks you are taking, and the potential outcomes. You can significantly decrease the likelihood of triggering an avalanche by steering clear of steep, rocky, open, heavily wind-affected terrain.

Regioni coperte