Lawinenlagebericht

Olympics

Northwest Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Drier weather, soft snow, and a little sunshine will make the mountains feel very inviting. However, a recent storm and a known buried weak layer of snow should keep conditions dangerous. You could trigger an avalanche on steep open slopes, especially where the wind drifted the snow deeper.

Lawinenprobleme

  • Wind Slabs

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

    Moderate to strong winds accompanied the bulk of this storm and likely formed new wind slabs on a variety of features. Calm winds and a skiff of new snow could make this problem a little harder to see than normal. Fortunately, there should be plenty of visual clues that help you anticipate wind-loaded areas. Cornices, scoured slopes, and drifts behind trees/rocks will help you locate and avoid these potential wind slabs. 

    In some locations, a layer of surface hoar was buried prior to this storm. If these wind loaded slopes sit over this weak older snow, avalanches may fail easily, trigger remotely, and break above you. This makes them very different and more dangerous than the common wind slabs you oftten see in the Olympics. Give wind-loaded slopes a wide berth.

    (12/9/2022)

    Scoured slopes and sculpted snow show evidence of wind transports snow. 

    Photo: Sam Luthy Siemens

  • Storm Slabs

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

    This storm dropped a foot or more of snow in the Olympics. Normally weaknesses within the new snow heal fairly quickly here in the Northwest. However, you could still trigger storm slabs, especially on very steep slopes or near convex rollovers. Hand pits, uptrack tests, and small slopes can help you see how the snow reacts. If it fails easily or cracks, avoid steep open slopes. With the sun coming out, it's hard to say how the surface slab may change, but it could create particularly touchy conditions. 

    Similar to the wind slabs, a layer of buried surface hoar only makes this problem more challenging. Now with 15-24in of snow on this layer, any avalanche could easily grow large enough to bury and kill you. It will be hard to decipher exactly where this buried layer could exist. Consider sticking to smaller and less consequential terrain to manage this more complex snowpack.

    (12/8/2022)

    Buried surface hoar was even found in shallower snowpacks on more wind stripped aspects. 

    Photo: Sam Luthy Siemens

Avalanche Discussion

The draw of the soft snow is palpable. Unfortunately, a known buried weak layer and a recent significant storm should cause you to pause before jumping into steep terrain. This may not be the normal post-storm powder day. NPS rangers and avalanche professionals found a layer of buried surface hoar on all aspects Thursday and Friday. Since this weak snow was protected from the brunt of the storm, there is no reason to think it went away. Now it’s just deeper. So far we haven’t heard of any avalanches on this layer, but that could change. You can use snow profiles and snowpack tests to confirm the presence of this layer, but they don’t prove its absence. Similar snowpack conditions have been reported in the Stevens Pass, Snoqualmie Pass, East Central, West South, and Mt Hood zones. 

Other observations from Hurricane ridge this week show small cornices, scoured ridges, and sculpted snow features all telling the story of the recent winds. 

Even though it feels like winter, plenty of exposed and shallow buried obstacles still exist to make travel more challenging and potentially dangerous.

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