Lawinenlagebericht

West Slopes Central

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Snowfall is finally winding down after 2-3 feet of snow fell in the last 5 days. You can still trigger avalanches in steep terrain, the most concerning ones being in wind-affected areas. If you find areas of firmer, wind-affected snow, avoid them on steep slopes.

Lawinenprobleme

  • Wind Slabs

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

    Wind died down in the last day, and many of the shallow slabs that were failing naturally and with human triggers stabilized. Especially at upper elevations, remain alert for wind slab avalanches. There is more uncertainty at upper elevations, where fewer people traveled in recent days. As you gain elevation, you may encounter thicker ones.

    Identifying wind slabs was difficult in recent days, as light winds and low-density snow created very soft slabs. They may also have a coating of non wind-affected snow on top of them. These deposits usually form under cornices or drift around features, such as on lee sides of ridges, near the bases of cliffs, and on gully sides. Travel out on smaller slopes to test them before you move to larger ones. Pay attention to obvious clues such as cracking and slightly thicker feeling snow. If you find wind slabs, avoid them on slopes steeper than 35 degrees.

    (12/23/2021) A small wind slab avalanche which occurred on a test slope.  Photo: Andrew Kiefer

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–1.5

    Several feet of low density snow in 5 days is a lot. Even on non wind-loaded slopes you could encounter soft storm slabs. They may propagate out for a distance, or possibly act more like a dry loose avalanche, simply picking up snow and running in the surface layers. Likelihood of encountering a natural one of these is reducing now that snowfall abated. It is possible that you can trigger one if you’re on a steep slope. 

    Start your day with smaller slopes to determine whether your impact will cause any avalanches. If you’re entering steep terrain, consider pushing a bit of snow down first to see how the surface layers react. Depending on your experience, encountering small amounts of this soft running snow, or sluff, may feel acceptable, but stay alert for, and avoid any larger amounts which could pose more of a threat to you.

    A small, shallow soft slab avalanche like one you may encounter on Monday.

    Photo: Irene Henninger

Avalanche Discussion

I traveled to Lake 22 on Sunday and unsurprisingly encountered a lot of light, fluffy snow and it was still snowing. At lower elevations (2000ft) the main avalanche problem that I encountered was low-density snow running easily on any steep surface at about 4 inches deep. As I walked through an open meadow, I encountered a debris pile from an avalanche that had probably ran in that surface layer within the last hour or two, and was about 3 feet deep.  As the trail continued along similar terrain for the next several hundred feet, I didn't feel comfortable traveling by myself through that area, so I headed back to the treed and not-so-steep terrain at the lower elevations.  As we shift away from the recent storm, very cold temperatures are settling into the region. Prepare for your outing with warmer layers than usual. 

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