Bulletin d’avalanche

Snoqualmie Pass

Northwest Avalanche Center
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Danger d’avalanche

Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Brrrrr! It’s downright frigid at Snoqualmie Pass. With all the cold dry recent snow, look for spots where east winds formed new slabs, possibly in some unusual locations. If you see smooth pillow-like drifts, steer around them and seek out lower angled or less wind-affected terrain.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    East wind events like we experienced on Tuesday can form slabs in some unusual locations at the Pass. These types of wind patterns don’t often form widespread issues, and you’ll need to look feature by feature as you travel to determine if the slopes in front of you may hold potential wind slabs. Textured surfaces and sharp drifts can serve as simple clues pointing towards potentially wind-loaded slopes. Since these slabs formed on Tuesday, they are still fresh and may trigger easily under your weight. Fortunately, most of them should also be relatively small and shallow. You’re most likely to encounter a large wind-loaded pocket on exposed terrain, near the base of cliffs, or in rock-walled gullies. Be leery of any feature where you suspect the east winds formed slightly firmer and thicker slabs.

    (2/18/2022)

    Example: Wind affected surfaces and cornices on Chair Pk shoulder. 

     

    https://nwac.us/public-obs/11451/

    Photo: Public Observation

Avalanche Discussion

Wednesday could be one of the coldest days of the winter at the Pass. While sunshine and light winds may help it feel a bit warmer than the air temperatures suggest, it’s still going to be extremely chilly. Make sure you prepare for this colder than normal weather and watch for cold-related injuries. 

We’re a couple of days out from this past weekend’s storm, and the snow has started to change. Besides the east wind transporting snow, we’ve seen a thin breakable sun-crust form on the surface of slopes that receive direct sunshine. In shaded areas, the recent snow remains very light and unconsolidated. On Wednesday, this pattern should persist. You may see a few very small natural loose avalanches on sunny slopes, but these possible slides should be very limited given the extremely cold temperatures. 

Observations from NWAC staff, avalanche professionals, and our public observations site report very similar conditions all across the zone. At mid and upper elevations about 20” of storm snow sits over a very thin crust buried on 2/19. This layer can be difficult to find in some locations, but you can typically feel it 1-2” above the easier to identify Valentine’s Day crust. While numerous slab avalanches occurred during the storm, any weaknesses in the recent snow should be gaining strength. While we don’t expect any current avalanche concerns on these deeper layers, we are keeping our eye on the snow around the 2/19 and Valentine’s Day crusts.

Régions couvertes