Lawinenlagebericht

West Slopes South

Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Another warm and rainy day Wednesday will keep the snowpack from freezing and gaining strength. Wet avalanches could grow large, cornices may fall, and it's uncertain how old weak layers will handle the ongoing thaw. Travel cautiously and build in a wide margin for error.

Lawinenprobleme

  • Loose Wet

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

    Light rain will continue to destabilize the snowpack. Wet avalanche activity looks to continue, with the most reactive conditions expected for the first half of the day Wednesday before winds increase in the afternoon. You may see both wet slab and wet loose avalanches that could gouge into the snowpack, build significant mass, and run far downslope. A wet slide in motion could even trigger deeper weak layers resulting in a much larger and destructive avalanche. When you find wet sticky snow or see new avalanches, dial it back and stay off of and out from under steep slopes. We expect most of the natural avalanche activity to stay small, but you could see a larger avalanche in big complex terrain and where more snow accumulated over the past few days.

    (3/1/2022) Example: A wet slab avalanche from our last rain on snow event.  Photo: Dallas Glass

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–2.5

    It’s hard to say exactly how the persistent weak layer will react in the short term with the ongoing thaw. It will be best to step back during this rapid change and steer clear of upper elevation start zones. Cornices could even fall acting as huge triggers on slopes below. Avalanches this past week have been remotely triggered from adjacent terrain and ridgelines. So, put a buffer of terrain between you and large, steep slopes on W-N-E aspects at upper elevations.

    (3/17/2022)

    A large avalanche that failed on 3/16 near Crystal Mountain. This slide failed on the 3/8 facets and ran on the Early March Crust, with debris crossing a popular traverse track.

    Photo: Robin Pendery

Avalanche Discussion

Skies cleared Tuesday afternoon as the strong March sun beat down on a soggy snowpack with mountain temperatures reaching over 50F. The rapid thaw caused significant settlement with the Paradise weather station showing a 12in loss in the overall height of snow over the past 24 hours. Widespread wet loose avalanche activity was reported in adjacent zones and similar conditions are suspected in the West South. Wet avalanche activity may have already peaked, but will likely be ongoing with additional rain, warming, and sunshine through the end of the week.

Over the past several days, human-triggered avalanches and audible whumpfs have been observed across the West South zone. A layer of sugary facets just above the Early March Crust has been the culprit in all of these events. In most locations, this layer is now 2-4ft below the surface. While this may make it harder to trigger, any resulting avalanche could easily be big enough to bury and kill you. Unfortunately, there aren’t a lot of ways to easily rule this avalanche issue out. Tracks on a slope and a few snowpack tests do not mean it's safe. Best to just give this hard-to-manage problem the respect it deserves. 

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