Bulletin d’avalanche

West Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 7 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Expect heightened avalanche danger first thing Sunday morning, with fresh wind slabs possible anywhere downwind of big open slopes, convex rolls, and ridgelines. If you’re seeing fresh drifts, sharp cornices, or punching into deeper-than-expected new snow, you’ve likely found wind loading; dial it back and move to lower-angle terrain. The southern volcanoes will see the bulk of the precipitation, thus a potential for larger slabs.

Problèmes avalancheux

  • Wind Slabs

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

    By Sunday morning, freshly formed wind slabs will be your main concern, primarily at middle and upper elevations. Upper mountain snowfall is expected to continue overnight Saturday, accompanied by sustained moderate to strong wind, redistributing any fresh snow onto terrain downwind. Most slabs should remain on the smaller side, but areas that see heavier snowfall and stronger wind could produce larger wind slabs. With stronger winds at upper elevations, expect some atypical loading patterns, drifts forming mid-slope, well below ridgelines, and even in between trees.

    The overall danger will depend on how much snow accumulates and how efficiently the wind can move it. As you travel, track the depth of the new snow and how it changes with elevation and aspect. If you’re moving from scoured, firm surfaces into pockets of deeper, denser snow, you’ve likely entered wind-loaded terrain. Fresh cornices, wind lips, and active blowing snow will point you in the direction of loading. When in doubt, favor wind-sheltered terrain and slopes under 35 degrees.

    (12/21/2025)

    A small natural wind slab avalanche on Panorama Point. E, 6700ft. This slide like occured 12/19 or 12/20. As they often do, this wind slab formed on the lee side of a ridgeline.

    Photo: Andy Harrington

Avalanche Discussion

It may not look like a winter wonderland just yet, but it’s good to see snow returning to the West South. Snow levels hovered around 5,500 feet Saturday, with a few inches accumulating across most upper-elevation terrain. Moderate to strong southwesterly winds blew along the ridgelines throughout the day. Observers in the Crystal Mountain area reported active blowing snow and periods of poor visibility, while a nearby weather station recorded wind gusts up to 60 mph in the afternoon.

Precipitation will continue Saturday night, tapering off sometime after midnight. It’s less clear whether snowfall will linger into Sunday, but if it does, a bonus few inches aren’t out of the question. Snow levels will gradually fall overnight, potentially bringing snow to lower elevations, assuming the precipitation hangs on long enough for the cool down to take hold.

Before this storm, snow surfaces were quite firm across the zone. These old, firm surfaces could act as an efficient bed surface for newly formed wind drifts and slabs, though limited new snow should keep most of them on the smaller side. That being said, the most likely area of larger wind slabs will be focused on the southern volcanoes, White Pass, and the Paradise area. These zones will see more precipitation than the rest of the zone, with the chance of continued snowfall into the day on Sunday. If you're headed to higher terrain in these areas, be prepared for greater wind loading, and potentially more sensitive slabs. 

Régions couvertes