Lawinenlagebericht

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Sawtooth Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

Heavy snowfall and strong winds have created very dangerous avalanche conditions. Human-triggered avalanches large enough to bury people, snap trees, or destroy structures are very likely to occur. Slides can be triggered from long distances away from the slope that releases. Stay off and out from below steep slopes—slopes steeper than about 30 degrees. 

The backcountry AVALANCHE WARNING does not apply to the HWY 21 avalanche program. 

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1.5–3

    You're very likely to trigger large avalanches on many slopes. These slides will break widely on a weak snow interface, including slick facets, crusts + facets, and surface hoar. Dangerous avalanche conditions exist on all aspects and elevations, including areas sheltered from the wind. 

    Anticipate touchy conditions that worsen in windier terrain. Persistent Slab avalanches can release in surprising ways. You can trigger them from flat or low-angle terrain long distances away from steep slopes, and they can break far above you. Snowpack cracking and collapsing are obvious clues that the slab + weak layer combination you've encountered is unstable. 

    ADDITIONAL DISCUSSION: The shallower Persistent Slabs described above have the potential to step down to release a massive, destructive 4+ foot thick avalanche. These slides would fail on persistent weak layers in the middle or base of the snowpack. The chance we see these beasts will only increase as the storm intensifies again this evening and tomorrow.  

    (2/26/2024) This slab avalanche released during an intense period of precipitation on Monday. Today's storm will add to these slabs, creating dangerous conditions on many steep slopes.  Photo: VandenBos

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2

    Yesterday, Ben remotely triggered a large avalanche from a safe ridgeline in the Boulder Mountains. The avalanche was about 250' wide and released on weak snow near the ground (video at right/below). With continued snowfall today, 36-hr storm totals will reach 1.5-2.5' by nightfall. Strong to extreme S and SW built fresh, sensitive wind slabs in exposed terrain. Given the intensity of the wind, anticipate these slabs on any open slope, including the mouths of main drainages and roadways that typically funnel wind.

    While dangerous on their own, these fresh slabs are likely to release on the persistent weak layers described above. Cornices will be sensitive and may calve off to release slabs on the slopes below. Drifts, dunes, rippled snow surfaces, and chalky snow pillows are clues that the wind has been at work.

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