Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

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

Kernpunkte

“It’s deep,” is the most common phrase heard to describe current conditions in the West South zone. With all this snow, and more on the way, don’t let powder-fever get the better of you. Give the snowpack time to adjust to the recent storms by staying off of large steep open slopes.

Lawinenprobleme

  • Storm Slabs

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

    Several human triggered avalanches have been reported each of the last 3 days from multiple locations around the West South Zone. Honestly, it doesn’t get much more obvious than that…recent avalanches, significant new snow, and strong winds equal potentially dangerous conditions. Let the snowpack heal and gain strength by steering around large steep open slopes. With so much new snow, small slopes and uptrack tests may not give you the information you need about potential avalanches. You’ll want to consider all the snow above the prominent 4/8 crust and its many potential weaklayers. So, you’ll have to dig with your hand or shovel to look for strong over weak (firm over soft) snow or layers that fail easily. If you observe these characteristics, you’ve located the storm slab problem. 

    Near ridgelines, plenty of evidence of wind-affected snow can be seen. You may find avalanches trigger more easily and/or are much deeper in these areas. Since the wind blew from nearly every direction during these storms, you could see wind drifted snow on all aspects. Monday, an NWAC forecaster intentionally triggered avalanches on opposite sides (E and W) of the same ridgeline, highlighting this point. Unless you’re standing on an icy crust in a wind-scoured spot, anticipate that you could trigger a slab avalanche.

    (4/11/2022) A small but deep slab avalanche was triggered by a cornice fall on this wind stripped slope. The lines below are wind drifts. W, 6400', SS-ACc-D1-R1-S Photo: Dallas Glass

Avalanche Discussion

While this stormy period is starting to wind down, it’s not over. The West South zone could see 4-8 inches of additional snow by Tuesday afternoon. With cold temperatures and high snow to water ratios, we wouldn’t be surprised if a few areas received a bit more snow than predicted. This will add to the very impressive storm totals since April 8th. As of Monday afternoon, most locations have received 24-40 inches of snow! Needless to say, many reports are of deep powder conditions This new snow accumulated over the very prominent 4/8 crust. You can use this snowpack marker to focus your observations on the upper snowpack. It will also help you quickly locate deeper more wind drifted slopes and shallower wind stripped areas. At this time we don't expect avalanches to fail on older snow layers below the 4/8 crust. 

The big question for Tuesday’s avalanche forecast is the sky. Right now, we expect mostly cloudy skies with relatively cold temperatures. However, it’s April. So, it won’t take much sunshine to cause this cold dry new snow to start to fall down. If you experience significant periods of sun, expect natural loose avalanches. The snow shedding from trees, rollerballs, and small teardrop-shaped slides should alert you to this possible change in the avalanche danger. Natural loose avalanches will be most common on steep slopes receiving direct sunshine. If you notice these conditions developing, get out from under similar terrain.

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