Bulletin d’avalanche

West Slopes North

Northwest Avalanche Center
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Danger d’avalanche

Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 8 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

We’ll receive just enough snow to nudge avalanche danger upward on Friday. By the end of the day, a few inches of new snow may drift into thicker deposits at mid and upper elevations, where you could trigger an avalanche and be taken for a rough ride. At lower elevations, rising snowlines may lead to small wet avalanches in the new snow.

Problèmes avalancheux

  • Wind Slabs

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

    Most avalanche activity will likely stay within the new snow. Early in the day, there may not be enough snow to elevate the danger, but expect conditions to change as snowfall continues. Underlying surfaces vary widely, so wind slabs may behave differently depending on where they form. You might find crusts, old wind slabs, or low-density snow beneath the new layer. You can dig down with your hand or pole to test how well the new snow sticks to the layer beneath it. 

    Search for thicker, heavier drifts—often textured or pillow-shaped— at mid and upper elevations. If drifts grow deeper than about 6 inches, slide easily on the layer beneath, or you see red flags like shooting cracks or recent avalanches, steer around steep slopes where these drifts exist. Even if some avalanches aren't big enough to bury you, they could cause serious harm if you are in a terrain trap. 

    Example photo: Wind drifted snow tends to catch around features like rock outcroppings, where it's more likely you can trigger an avalanche. Note the wind-transported snow visible in this photo. 

  • Loose Wet

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

    We expect wet loose avalanche activity to mainly exist in the new snow that falls. As freezing levels rise during the day, any snow that recently fell might get moist are slide or roll downslope. 

    Most avalanches will probably stay small. They may occur with a human trigger if you're on sticky snow. The old snow layer might provide a good sliding surface, or maybe the new snow will pick up enough mass that it could take underlying moist layers with it, too. 

    If snow around you gets moist, wet, or sticky, scan nearby steep slopes to see if any new rollerballs or small slides are coming down them. Continue this process throughout the day as temperatures creep upwards through the lower elevation band. If you notice any wet avalanche activity, consider steering around similar steep slopes or areas beneath where these avalanches could run. 

     

    Example photo: Rollerballs running in surface layers. These could be precursors to small wet loose avalanches. 

Avalanche Discussion

A few newer glide cracks and one glide avalanche were recently seen in the Baker backcountry. There's a very small chance cracks may continue to expand or avalanche, so if you see any, consider giving them a wide berth below them. 

I sledded at Canyon Creek on Wednesday and Thursday and did not find lingering instabilities in the old snow. I also didn’t observe any newly formed wind slabs, and wet avalanche activity was mainly limited to rollerballs that had already run. In contrast, observers high on Mount Shuksan, mainly above our forecast elevations, reported reactive, newly formed wind slabs Tuesday night into Wednesday morning—highlighting how variable conditions are across the zone. 

After several days of high pressure and a strong inversion that affected some areas more than others, more unsettled weather is on the way. Expect conditions to change. As the first precipitation arrives, pay close attention to how new snow bonds to existing surfaces. Small temperature shifts could quickly change avalanche problems from dry to wet, requiring ongoing evaluation and flexibility in your terrain choices.

Régions couvertes