Bulletin d’avalanche

West Slopes Central

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Lingering glide avalanche activity is our main concern as cooler temperatures approach. This is a low likelihood yet high consequence scenario, where it's still best to avoid traveling beneath glide cracks and spots where the snow has buckled. We may get a few inches of snow up high, and variable punchy and crusty surfaces will exist in many other areas. 

Problèmes avalancheux

  • Glide Cracks

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

    This is the tail end of several days of warm, wet weather. Glide avalanche problems tend to linger even as temperatures begin to cool. Be on the lookout for overhead glide cracks or wrinkles of snow. Avoid traveling beneath these features, as you never know when they might just fail and avalanche. Even though the probability of this happening is quite low, the consequence of one of these failing and releasing a large avalanche could be catastrophic for you.

    Once we have a few days of cooler weather this problem should subside. Likewise, any other overhead hazards like cornices or snow slabs sitting on exposed rock features are more likely to release while the temperatures are warmer, so avoid traveling under these features as well. Snow levels have crept up in recent days with the rain and warm temperatures, so most of the lower elevations don't have enough snow to be able to produce sizeable avalanches. If you still encounter deeper swaths of continuous snow cover at lower elevations, avalanches could still result. 

    (12/4/2024)

    Glide activity on a steep south-facing slope in the West Central zone at about 5000ft from this year's previous warmup. You'll likely see something similar on Saturday. Avoid traveling beneath these features. 

    Photo: Irene Henninger

Avalanche Discussion

Freezing levels will rapidly drop to about 4000ft on Friday, and forecasts are calling for precipitation. It may start as rain but rapidly transition to snow, possibly enough for a few inches at upper elevations. If you make it to upper elevations, you might be able to trigger small avalanches in wind drifts on steep slopes. Or, if a few inches of damp snow falls on a still wet underlying layer, you could get shallow moist, loose avalanches running on the old snow surface, possibly entraining some of that old snow layer if it's soft. 

Most snow surfaces are irregular, and you can expect to find rain runnels and varying levels of punchy or crusty snow at all elevations. Expect challenging travel conditions if you get out. With the dropping freezing level, the wet crusts will begin to freeze up and get harder as the day progresses, especially if you're making it to the mid or upper elevation bands. 

An intense storm Tuesday night brought 1.5-3" of rain to the zone with gale force winds. Although observations are limited, there was likely a lot of wet avalanche activity during the event. Since then, avalanche activity has subsided but not quite enough for the danger to transition to low. If you make it into the backcountry, please share with us what you find so that we can write better avalanche forecasts for you. You can submit observations HERE. 

Régions couvertes