Bollettino valanghe

Soldier & Wood River Valley Mtns

Sawtooth Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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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

    Triggering a large, 1-4 foot thick slab avalanche that breaks widely remains a worrisome possibility on many slopes. Avalanche activity during major storms of the past two weeks was widespread, occurring on all aspects. Many 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). On Tuesday, a large persistent slab avalanche was triggered from a distance, releasing on a heavily wind-loaded slope in Croy Canyon (observation). 

    You may or may not 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. 

    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 (see photo at right/above).

    (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
    Possible
    Dimensione
    1–1.5

    Stiff, icy crusts at the snow surface will quickly melt in the powerful March sun, bringing on the threat of wet snow avalanches. These slides start at a point and fan out as they travel downslope and gather speed and debris. Today's southerly winds may help to cool the snow surface, muting the impacts of this problem. Snow on shaded aspects at lower elevations may warm and melt with today's warm temperatures. 

    If the snow you are moving through is melting and becoming wet, these slides are on the menu. Pay close 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

SLEEPING ELEPHANTS

The Avalanche Danger has dropped to MODERATE today. This drop in danger is not an indication that avalanche conditions are now safe. The drop in danger is taking place because the likelihood of triggering a slide is gradually decreasing. Decreasing, but not going away. 

Storms over the past two weeks produced widespread avalanche activity. Avalanches were failing continuously in the new snow, but the massive avalanches that failed on persistent weak layers are the type we are most concerned about now. Days without snow have given the snowpack a chance to catch its breath and the bond at these weak interfaces is slowly gaining strength.

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 find yourself in quite a bad spot. Our snowpack is similar. You'll move around on the surface, enjoying the soft snow and dodging the crusts. There won't be many or any indications that there is weak, unstable snow underneath the thick slabs at the surface. And, more likely than not, you won't trigger a massive avalanche. However, if you do, there is a good chance that you won't be around to tell the tale.

Enjoy the sun and the snow-covered mountains, but think about the sleeping elephants when you're out there. You can significantly decrease the likelihood of triggering an avalanche by steering clear of steep, rocky, open, heavily wind-affected terrain.

Regioni coperte