Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
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

Strong winds and recent new snow is starting to test our weak upper snowpack. You’ll be able to trigger the largest avalanches in wind-drifted snow or closer to the Cascade Crest, but still be suspicious of sparsely treed, sheltered terrain that may harbor weak, sugary facets under the recent snow. 

Problèmes avalancheux

  • Wind Slabs

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

    Strong winds and recent snowfall will keep wind slabs ripe for human-triggering on Sunday. Expect these wind slabs to be larger and more consequential in the western parts of the zone. Some of these wind slabs have likely formed over variable crusts or facets and could break in surprising ways if triggered. 

    You can use visual clues like blowing snow and textured, rippled surfaces to help you identify wind loaded features. You’ll commonly find these slabs on the down-wind side of ridges, below cornices, or even on mid-slope convexities due to strong winds. The combination of recent loading and a weak upper snowpack should have you avoiding steep, slopes that appear wind loaded.

    (2/1/2025)

    Blowing snow, fresh drifts, sharp cornices, and rime all point towards wind loading along this ridgeline. 

    Photo: Dallas Glass

  • Storm Slabs

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

    This problem will be most concerning in areas that received more recent snow closer to the Cascade Crest like west of Bumping Lake and the North Fork of the Tieiton. Recent snow fell on a weak upper snowpack, so storm slabs may stay reactive to the weight of a human and could break in surprising ways if triggered. 

    The usual strategies and tricks you use to manage risk might not be reliable, given the variation in snowpack structure below the new snow. Some slopes might produce no avalanches or smaller slabs. On other slopes, even those adjacent, you could trigger unusual avalanches that propagate widely, release when you are in the middle of a slope, or might even be triggered from below. Be especially wary of skiing into steep open glades in northerly terrain. Even a small avalanche could push you into unwanted terrain. 

    (2/1/2025)

    Any triggered storm slab could break into old snow and become a larger avalanche. This intentionally triggered persistent slab, propagated the entire width of the feature. It failed on facets over a thin crust. ENE, 6200ft, SS-ASc-D2-R3-O, 20-24 in deep, 200 ft wide.

    Photo: Dallas Glass

Avalanche Discussion

The East South has picked up 7-12 inches of new snow depending on where you’re in the zone. The Bumping Lake and Chinook Pass area was favored with this last storm, so look for more dangerous avalanche conditions the closer you move to the Cascade Crest.

Observations have been sparse in the East South, but an NWAC forecaster traveling in the White Pass area reported triggering several storm slabs and one persistent slab that broke into facets over a crust (NE, 6200 ft). Crown depths ranged from 1.5 - 2 ft thick. This is the first type of avalanche that we’ve seen of this kind since the storm commenced. With a similar structure in the east-south, shape your travel decisions conservatively. 

Prior to this storm, avalanche forecasters and backcountry observers consistently reported weak facets on north - east aspects at all elevations. Other aspects held facets, but also more surface crusts. The extended dry spell is unusual for the Pacific Northwest, so be suspicious of the snowpack as new snow continues to fall in the coming days. 

Multiple long-time avalanche professionals have mentioned that the last time we had a similar snowpack was in 2017-2018, which resulted in 7 deaths throughout the Cascades in roughly a week. You can read the accident reports here to re-familiarize yourself. Needless to say, many professionals are on edge about how the next few weeks are going to play out. 

Observations help fuel a more accurate avalanche forecast. Let us know what you see by submitting an observation here

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