Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist last year abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The likelihood of triggering a slab avalanche is decreasing, but you can still trigger one in the right place. Investigate the bond of new snow layers before committing to steep terrain. Choosing lower-angle slopes is the easiest way to reduce risk. If the sun comes out in force, expect to see wet avalanches.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1.5–2.5

    For the most part, Thursday night's new snow has bonded well and yielded only a few human-triggered avalanches. The counterpoint to this is a series of natural avalanches on southern aspects that released during the storm. All are suspected of having released on or near a slick crust buried on March 19th.  A very large natural avalanche was reported from upper-elevation, wind loaded, northerly terrain near Glacier Creek as well.

    Don’t assume you won’t trigger an avalanche on Saturday. Test slopes may or may not be useful. Hand shears might provide information about the bond of new snow to the layers below. Snow profiles will be helpful if done in representative terrain. When in doubt just pick a lower angle, more supported line. You can also reduce risk by sticking to slopes with no consequences, like trees, cliffs, or rocks in the runout below.

    The likelihood of triggering one often increases as slabs warm through the morning. If there is more than 6” of fresh snowfall, you could find shallower slabs just about anywhere.

    Example of a slab avalanche that released over a sun crust. Photo from prior winter.

     

  • Loose Wet

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

    There is plenty of fresh snow lying around that will have a bad reaction to strong sun. Periods of clear-ish sky and sun might be brief, but the March sun is powerful, and it won’t take much to warm snow surfaces. Avoid travel on or directly under steep slopes where you see fresh rollerballs or small wet avalanches.

    Cornices are now quite large and looming and getting primed to come down with sun and warmer temperatures. They are quite destructive on their own and can also trigger a slab lower on the slope. Don't linger below them.

    (2/14/2023)

    Wet avalanches often initiate in steep rocky or treed terrain. They can also trigger slabs lower on the slope.

    Photo: Robert Hahn

Avalanche Discussion

Observers from around West North all had some amount of avalanche activity to report. The biggest news was the natural avalanches observed on Herman in the Baker BC, and also in Glacier Creek. Human-triggered avalanches tended to be small in size and more stubborn throughout the day. Snow amounts were not shabby, with well over 1' of new snow in many areas.  Snowfall and wind speeds died off around sunrise but then picked back up at the end of the day.

These avalanche observations highlight the consistency of snowfall across the zone. They also are a great example of the combination of lingering weak layers, slick, crusty bed surfaces, and other layering combinations that are out there.  With a bit more snowfall, then maybe some sun on Saturday, and then rain and potentially High danger on Sunday, it won't be a weekend to take mountain travel lightly. Have a plan in place to completely avoid avalanche terrain if you find volatile, dangerous conditions, especially if you head out for multiple days.

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