Lawinenlagebericht

West Slopes North

Northwest Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

It is likely that you could trigger an avalanche in wind drifted snow, especially by the end of the day as snowfall intensifies. Steer around steep, wind-loaded areas where you notice thicker deposits of snow or see visual clues such as textured surfaces, or if you initiate cracking snow. Snowline is wavering in below treeline elevations, and small wet loose avalanches could occur naturally or with a human trigger at these lower elevations in the wet snow. 

Lawinenprobleme

  • Wind Slabs

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

    After our first bluebird "warm" day in weeks, we're right back into another April winter storm. Weather will intensify throughout the day, and the avalanche danger will slowly rise as more snow accumulates and moderate to strong winds redistribute the snow. You're most likely to trigger avalanches in steep, wind-loaded spots. These locations tend to be on the leeward slopes near ridges, in gullies, and around rocky outcroppings. Six inches to a foot of snow is forecasted, and drifts could grow well over a foot deep by the end of the day. 

    Search for signs of wind loading by feeling for firmer, thicker snow beneath you. Visually hunt for clues such as textured or featured snow surfaces and actively blowing snow. Don't ignore obvious signs such as recent avalanches, cracking or whumphing. Where you encounter drifts thicker than 6 inches, steer around slopes greater than 35 degrees, as it's likely that you could trigger an avalanche. By the end of the day drifts will have grown deeper and possibly more reactive, so continue to evaluate as you travel. You're likely to find wind slabs most reactive at exposed higher elevations, but they could reach as low as the upper reaches of the below treeline band. 

    (4/17/2022) Cracking in newly wind drifted snow on Mt Shuksan, when winds picked up on Sunday. Photo: Matt Primomo

  • Loose Wet

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

    Rain and a wintery mix at below treeline elevations could lead to small wet loose avalanches. You'll probably find that they are only running in the surface snow, a few inches deep. Small natural avalanches might occur on steep slopes, but it is possible that you could trigger one in damp snow. They could run in older snow that is rained on, or in moist newly fallen snow. If you're sinking ankle-deep or more in wet snow, or if you notice rollerballs running frequently, or any wet avalanches, steer around steep slopes and the runouts beneath them. 

    (4/16/2022)

    Recent small point release rollerballs, which you might see in below treeline elevations on Monday. They very well could be small avalanches, rather than just rollerballs. 

    Photo: Irene Henninger

Avalanche Discussion

Surface hoar was found by observers in the last few days, and it could have been buried by the 3-6 inches of snow we got Saturday night on the colder north-facing slopes. Facets were also discovered both near the old snow surface, and above the 4/8 crust, buried 1-3+ feet down. Not only this, but graupel layers with clean shears were found in the old snow layer about 6 inches down, and all these concerns are leading to a complex snowpack above the 4/8 crus.  With snow already coating the old snow surface, and more coming Monday, we might find ourselves with more reactive slabs on north-facing slopes than expected. We could see avalanches stepping down to deeper layers, Possibly up to 3 feet deep. Keep this in mind during your travels on Monday. 

North-facing slopes managed to stay dry all week, but all other aspects were cooked in recent days. Many slopes are textured with refrozen rollerball bumps. The crusts could make for challenging travel, or they could make a good sliding layer for wind drifted new snow, if the crust is smooth enough. 

We got some great observations about snow conditions and recent avalanches (or lack of) on Sunday from different areas in the zone. You can check them out HERE and HERE. If you're getting out on Monday, don't hesitate to fill out an OBSERVATION so that we can learn more about snow conditions in different areas. 

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