Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The snowpack around the West South should be gaining strength, reducing the potential for avalanches on Thursday. We aren’t exactly entering the ice age, though. So keep wet slides on your mind anywhere you encounter a wet and punchy snow surface.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    On Thursday, we won’t be that far removed from a major wet avalanche cycle. Wet avalanches are always tricky to predict and sometimes occur long after the rain has stopped. If the snow surface is wet and punchy, keep them on your radar. On steep slopes, you may be able to push snow that gathers mass and fans out as it descends. 

    We suspect that most slab activity should be finished, but we won’t rule out a chunk of snow falling off a rocky ledge or a rogue cornice collapse.

    (12/18/2024)

    Wet avalanche debris coming out of a steep rocky area in the White Pass Backcountry.

    Photo: White Pass Pro Patrol

Avalanche Discussion

The numbers are in, and the West South got walloped during this week’s storm. The volcanoes received 4+ inches of water, with one Snotel site by Mount St. Helens recording 6.5 inches! Closer to the crest, roughly 3 inches fell. There was a mixture of snow, rain, and even freezing rain in places, creating a mess of our snowpack. And that doesn’t even account for the winds - which were significant Wednesday morning.

On-the-ground observations on Wednesday were limited, but our friends at the Cascade Volcano Observatory passed along information picked up by their seismic equipment. During the storm, very large (greater than D2) avalanches were recorded on Mount Rainier, Mount St. Helens, and Mt. Adams.

Crystal Mountain Pro Patrol reported several large crowns that failed naturally on N-NE facing terrain near the resort. White Pass Pro Patrol reported several wet avalanches in the surrounding terrain and plenty of damage due to the wind. 

Speaking of wind, if you make it to higher elevations, a few inches of snow may have drifted into shallow slabs. Our hunch is that there aren’t many pockets large enough to produce consequential avalanches, but don’t get tripped up by one.

This storm certainly didn’t help build snowpack depth. Be prepared for variable surfaces partially due to nighttime cooling and daytime warming. Difficult travel is expected with hazards such as firm crusts, rain runnels, frozen avalanche debris, swollen creeks, open holes, and exposed rocks/logs. In some locations, there’s a chance you could slip and go for a long uncontrolled slide. So travel with the appropriate gear and default to lower-angled slopes if the surface is firm and slick.

Régions couvertes