Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

Even though temperatures will cool slightly on Monday, you could still encounter dangerous natural wet avalanches. Snow may shed from very steep and rocky slopes with little or no warning. Look for routes that help limit the time you need to spend below these areas.

Problemi valanghivi

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–2.5

    It will take more than a little cool down to put an end to the wet avalanche issues. While these slides may be hard to initiate, they could occur naturally, especially with a bigger trigger. Snow shedding from rocks, a collapsing cornice, or a small loose slide could all get these bigger avalanches rolling. If they do, these slides may entrain wet heavy snow and act more like a bulldozer plowing down the mountainside. You don’t want to be in their way. Best to just let this cycle play out from areas away from steep open terrain. 

    Similar to this wet slab problem, you could see natural loose wet, glide, or cornice avalanches. All these “shed” style slides love to occur during prolonged warm and wet weather. Fortunately, the travel advice is the same, limit the time you spend under any overhead hazard. 

    (1/14/2023)

    Example: Large wet avalanche debris after a rain event earlier this winter. 

    Photo: Dallas Glass

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    Higher in the terrain you may find a much drier snowpack. While most of the warm wet snow should bond pretty well to the older surface, you could easily trigger avalanches in wind-affected terrain. Watch for blowing snow, sharp cornices, and textured surfaces to anticipate and avoid these wind-loaded pockets.

    These potential slabs will be the largest on the volcanoes, at higher elevations, and later in the day. So, if you start to find small wind slabs, as you ascend, expect them to become more difficult to manage.

    (1/18/2023) Actively blowing snow and sharp new cornices were visual clues available to help identify wind-loaded slopes. Photo: Andy Harrington

Avalanche Discussion

Temperatures will cool, precipitation ease, and winds decrease a bit on Monday. But, make no mistake, the warm and wet isn’t over. Even though this isn’t a huge storm by Cascade standards, it has been a very big change for, what at least was, a cold, dry, and layered snowpack. Predicting how the snow will react as the weather suddenly swings from winter to spring is very challenging and brings with it quite a bit of uncertainty. 

The nasty weather on Sunday severely limited observations from around the zone. Weather stations generally recorded 0.5-1.5 inches of precipitation, much of which fell as rain to near or above 7000ft. We don’t know if a natural avalanche cycle occurred. Let us know what you see on Monday by submitting an observation. 

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