Bulletin d’avalanche

West Slopes Central

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

Points saillants

Avalanche danger will remain on moderate as recent wind drifts may continue to avalanche with a human trigger. Wind is depositing snow in unusual places, and a few people have gotten surprised by triggering avalanches in neighboring zones in the last few days. Search for textured snow and heavier snow surfaces, and avoid these wind-drifted areas on steep slopes. 

Problèmes avalancheux

  • Wind Slabs

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

    On Friday in the West North zone,  the 5th rider down a slope triggered a large slab avalanche and managed to escape before taking a long, scary ride (OBSERVATION). There were also reports of two human-triggered avalanches in the Snoqualmie Pass zone (photos in media).  All these avalanches were triggered on scary, committing lines and taking a ride likely would have resulted in injuries, if not death. We're glad to hear those involved managed to avoid getting caught. A backcountry enthusiast made it out to Overcoat Peak on Saturday and noted extensive wind transport in the area, where conditions are likely very similar to the neighboring zones. 

    Avalanche danger is moderate at mid and upper elevations, which means human-triggered avalanches are possible. The current conditions aren't quite your average wind slab problem. Southeasterly winds have distributed snow into unusual locations and slabs have been tricky to identify with distribution and reactiveness, catching even experienced people off guard. Meanwhile, there are non wind-loaded areas that still holding onto nice dry powder.

    Choose your terrain wisely. Be sure to assess snow conditions before committing to a steep slope. Changes from non wind-loaded to wind-loaded areas might be abrupt, and some pockets may not react to your weight, while others may. It's been one more day and the amount of snow available for transport has dissipated, and slabs may be more difficult to trigger than in the previous day or two. We suspect new slabs will likely be less than a foot deep. We're not in the clear yet, so continue to avoid wind-loaded slopes greater than 35°.

    (2/16/2024)

    Small test slopes work great for seeing how reactive shallow wind slabs are. 

    Photo: Julz Holder - Grounding Truth

Avalanche Discussion

In the Highway 2 corridor on Thursday, I found good bonding above the Early February Crust (EFC), which was buried about a foot beneath the surface, all the way up to 5300ft on all aspects. I did find subtle weaknesses midway in the newer snow layers above the crust. We're getting inconsistent information in many zones, with avalanches that may be occurring on either the EFC or within the new snow layers above the EFC. Failures beneath new wind slabs and on these layers aren't out of the question. The good news is that these potential weaknesses are in the top foot or so of the snowpack, so you can easily dig down and isolate a column with your hand and see if any layers pop off easily. 

We'll be getting an inch or two of snow by the end of the day Sunday, which may drift into additional very small slabs. The new layer might hide older slabs that could still avalanche. Friday's intense sunlight means slopes on the southern half of the compass might have had small amounts of wet loose avalanche activity, and crusts are present on or just below the surface. 

If you make it into the backcountry, prepare for shallow, variable snow cover, with crusts and an abundance of holes in the snow that could catch you off guard at lower elevations. Send us an observation so you can help contribute to better forecasts in the zone!

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