Lawinenlagebericht

Galena Summit & Eastern Mtns

Sawtooth Avalanche Center
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Lawinengefahr

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

Very dangerous avalanche conditions exist. Large human-triggered avalanches are likely, particularly on slopes with stiff drifts near the surface. Slides can be triggered from flat terrain a long distance from where they release. Expect naturally occurring loose snow avalanches on very steep slopes that directly face the sun.

Lawinenprobleme

  • Persistent Slabs

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

    Large human-triggered avalanches are likely. These destructive 2-4 foot thick slides will fail on faceted snow on shadier slopes and crust + facet combinations on sunnier slopes. Yesterday, multiple large avalanches were observed in Baker Creek (observation). These slides fit the recent avalanche activity pattern focused on the compass's northern half (W-NW-N-NE-E) in middle and upper elevation terrain.

    Wind-blown snow and additional snowfall overnight will keep many slopes on edge. Slopes with stiff drifts near the surface are the most dangerous. 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. The only surefire way to manage this problem is to avoid avalanche terrain, especially slopes with terrain traps or severe consequences.

    This very large avalanche failed naturally sometime between Friday night and Saturday morning. The crowns span 2,000 feet of terrain and the slide ran over 1,000 vertical feet. The majority of the slope that avalanched faces NW.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    This zone picked up 5-15" of snow since Wednesday evening, accompanied by moderate to strong SW and W wind. Storm snow likely did not bond well where it landed on facets, crust + facets, slick crusts, and surface hoar. Expect to encounter a host of new snow problems. These range from 1-2' thick sensitive wind slabs at upper elevations to potentially touchy slabs and loose snow sluffs that fail readily in steep, sheltered terrain. Look for obvious signs of instability, like small recent avalanches or cracking and collapsing of the snowpack. Even smaller slides in sheltered terrain can have big consequences if they push you into terrain traps like stands of trees or a creek bed. Importantly, any smaller natural or triggered avalanche has the potential to step down to a deeper weak layer, releasing one of the Persistent Slab avalanches described above. ADDITIONAL DISCUSSION: This afternoon will be clear, sunny, and mostly calm. Expect naturally occurring loose snow avalanches on slopes that face the sun. Large, rocky, steep slopes are the ideal terrain for these slides. Starting at a point, avalanches will gain mass as they move downhill, running fast and far on slick crusts. Rollerballs or pinwheels are a clue that the snow surface is weakening, and loose snow avalanche activity may follow. 

Avalanche Discussion

The snowpack in much of this zone remains spooky. Storms in early February caused a widespread avalanche cycle. Avalanches had a choice of multiple weak layers to fail on. The largest slides released near the base of the snowpack on shaded slopes at middle and upper elevations. The 2-pronged shots of snowfall both Wednesday night and last night, along with loading wind speeds, have not given these weak layers a break. 

Today, conditions are at their worst on slopes where you find stiff drifts near the surface. These are most likely at upper elevations, but you may encounter them on some middle elevation slopes. While simple wind slabs are a concern, you have to assume that these slabs will also fail on weak snow deeper in the snowpack. The resulting slide will be large and unsurvivable. 

A long afternoon of sun will not only release natural loose snow avalanches but will rapidly consolidate the storm snow, quickly forming a denser slab on these weak layers that may be easy to trigger. Anticipate changing conditions today and think carefully about the consequences of being caught in an avalanche before committing to skiing or riding steep slopes.

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