Bulletin d’avalanche

West Slopes North

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré last year. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You can still trigger a slab avalanche on steep slopes holding recently wind drifted snow - and also in some shaded and sheltered areas as well. Evaluate stability in simpler terrain before stepping out onto bigger slopes. The likelihood of triggering or seeing an avalanche will be higher in the morning.

Problèmes avalancheux

  • Loose Wet

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

    A bit of clearing at dawn could carry into the morning and allow the sun to warm fresh snow. This round of loose snow avalanches is most likely to occur below cliffs and other steep terrain that sheds snow with warming. Most should be small, but big alpine features can still produce some long-running avalanches if the sun stays out for long enough. 

    Keep an eye on steep slopes picking up sun. Avoid traveling directly below areas where you see the first signs of wet avalanche instability like rollerballs, pinwheels, or very small avalanches. Full cloud cover will return as the next storm moves into the region.  If it's cloudy all day, then wet avalanches would be unlikely.

    (12/9/2024)

    Fresh rollerballs on sunny slopes are an early sign of wet avalanche instability.

    Photo: Toby Swimmer

  • Storm Slabs

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

    The storm is winding down. We should still see another 4-8” of new snow overnight with wind strong enough to blow it around. New snow layers should quickly gain strength through the day, but there are places to use extra caution.

    Steep, unsupported, wind loaded slopes are some of them. Use the pattern of drifting and scouring, cornices, and other clues to figure out which slopes are holding thicker or more sensitive slabs. Test slopes, wind lips, and other loaded features can provide information about the reactivity of fresh slabs.

    The other terrain type to watch out for are northerly aspects that are a bit sheltered from the wind. A weak snow surface of facets or surface hoar was preserved and buried in select locations, and a handful of avalanches are suspected of having failed at this interface. It’s not likely a widespread problem, but that doesn’t mean it's not out there. The biggest risk would be stumbling into one of these slopes with a gully or some other terrain trap below.

    Gully features like this are where you could get taken by surprise if a slab fails over a layer of preserved facets or surface hoar.

    (2/20/2025)

Avalanche Discussion

With a delay in the onset of precipitation, avalanche danger was very manageable for most of the day. When the storm did hit, it hit hard, with precipitation rates of up to 0.2” per hour around Baker Lake starting mid-morning. Strong winds lasted through the night and all day Sunday, with gusts up to 60mph at the Pan Dome weather station at Mt. Baker Ski Area. Precipitation amounts were nearly nothing looking farther east in the forecast zone.

An NWAC Forecaster in Canyon Creek and observers in the Baker Backcountry reported no new avalanches as of mid-afternoon. Natural and human-triggered slab avalanches that occurred on Saturday were reported from Canyon Creek. Low elevations are quite rained out and soggy with wet snow up to 4500-5000'. Slightly drier snow and better conditions were found higher in Canyon Creek, but reports from the Baker Backcountry indicated the wind had really torn up the snow surface, and riding conditions had worsened from the day prior.

Régions couvertes