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 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Watch for signs that the wind loaded snow onto the lee side of ridges or exposed features. When you see changes in the texture of the snow surface or notice sharp drifts, steer around and seek out less wind affect slopes.

Problèmes avalancheux

  • Wind Slabs

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

    Another windy day at the Pass Tuesday formed shallow new slabs. These fresh drifts may overlay older deeper deposits formed over the past few days. As a result, you could encounter wind slabs on a variety of aspects. Clues such as sharp cornices and drifts will help you find and avoid the shallowly loaded areas, but you may need to pay more attention to find the older slabs. If you notice the snow feels different underneath you or you find wind scoured slopes, these observations can help you locate the larger wind slabs. Steer around wind-loaded features and seek out lower angled or less wind affected terrain.

    (1/31/2021) This Wind Slab was intentionally triggered on a wind-loaded convexity in the Kendall area on Sunday. The slab initially broke on a density change before stepping down and failing on the 1/13 crust.

Avalanche Discussion

We should get a break from the recent active pattern on Wednesday. While wind affected snow poses the greatest risk to you, other potential avalanche hazards warrant a mention. 

We expect some sun breaks in the morning. These could produce piles of rollerballs or small loose wet avalanches on steep rocky slopes in the sunshine. If you see more of the sun than expected, loose wet avalanches could occur in more locations and produce a natural small avalanche cycle. If the sun doesn’t make an appearance, then loose wet avalanches likely won’t occur. Sky conditions could differ from west to east across the zone. 

Persistent slab avalanches continue to plague adjacent forecast zones (East Central and West South). While no avalanches have been reported in the Snoqualmie area, a similar snowpack structure exists. If you dig, you could find small weak facets above a very prominent 1/13 crust. In some locations, surface hoar and/or a thin crust accompany these sugary grains. Observations from professionals traveling in the zone indicated this layer show signs of healing but still retains its weak properties. Persistent weak layers can be tricky to forecast.  We don't expect the changes in the weather will tip the scale and cause avalanches on this layer. However, if you notice obvious signs of unstable snow such as shooting cracks or feel collapsing, dial back your terrain choices. Consider reading adjacent forecasts if you plan to travel in areas further east or in more remote parts of the zone where we have less information. 

Below 4000’, rain on Monday wet the upper snowpack. Cooler temperatures and a few inches of snow should help snow at this elevation refreeze. You could encounter challenging travel conditions including breakable crusts and icy slopes.

Régions couvertes