Bollettino valanghe

West Slopes South

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

If you’re out in the beautiful weather on Sunday, keep an eye out for areas where east winds have drifted the snow into unstable deeper piles. These slabs should be thicker and more pillow-like than the surrounding snow. Depending on your location in the zone, their depth may vary greatly. 

Problemi valanghivi

  • Wind Slabs

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

    Winds Saturday night should be strong enough to transport newly fallen snow into Wind Slabs for you to manage on Sunday. Look for wind-loaded features near ridgelines, on convex rollovers, or near rocky features such as gullies and the base of cliffs. The atypical easterly wind direction means that you might find slabs on different aspects than you are used to. Cross-loading of gullies or mid-slope loading are more prevalent during east wind events, so keep a keen eye. Freshly built cornices, textured surfaces, or drifts behind objects can indicate which direction the wind was blowing. Once that is determined, you can look for smooth pillow-like piles of snow or areas that look “fat” to help you identify wind-loaded features to avoid. Using small test slopes as you travel can give you an indication of how those wind-loaded features may be reacting to your weight. If you find that snow is failing easily or suspect a feature to be wind-loaded, simply steer around it by choosing lower-angled slopes.

    (1/22/2023)

    Scene of an avalanche burial and successful recovery on Mt. St. Helens. The rider was buried 6' deep and their snowmobile 10' by a Wind Slab a day after a storm.

    Photo: Shane Hummel

Avalanche Discussion

The West South was in the bullseye of Saturday afternoon’s brief storm that delivered a quick shot of snow and some gusty winds. As of Saturday afternoon, the volcanoes have picked up close to a foot as they outpace the crest. White Pass is next in line with close to 6 inches, while areas further north along the crest such as Chinook Pass and Crystal Mountain have received significantly less. Observations from the day are limited, but avalanche professionals near White Pass reported actively blowing snow and plenty of signs of wind transport at mid-elevations.  

We anticipate any avalanche on Sunday to be confined to the newly fallen snow above the 1/27 interface. In some areas of the zone, there could be a sun crust at this interface that could provide a good bed surface for avalanches to run on. In isolated areas, you could even find some buried weak snow capable of producing surprising avalanches.

While there are other layers of interest in the upper snowpack that we are tracking, we do not believe that any of them should present a widespread issue at this time. That said, you should focus any observations you make on the snow above the easily identifiable MLK crust and use that information to make terrain decisions.

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