Bulletin d’avalanche

West Slopes North

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 6 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Reactive wind slabs developed in the last couple days’ snow.  You can trigger an avalanche in the new snow layers, especially where they formed into thicker and more sensitive layers on leeward slopes.  Avoid slopes steeper than 35 degrees, specifically in areas where you notice thicker wind deposits, and travel quickly through the runouts beneath these slopes.

Problèmes avalancheux

  • Wind Slabs

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

    It is likely that you can trigger an avalanche in wind loaded terrain at higher elevations on Saturday. On Friday, observers saw avalanches failing in the new snow layers, and locations that were wind affected were the most reactive. Feel for thicker and stiffer snow, and look for textured or smooth, pillow-like surfaces to help identify where wind slabs are located. 

    Instabilities are settling out quicker in non-wind affected terrain as temperatures are warming. Keep storm slab avalanches at all elevations on your mind, and  regularly check shallow interfaces with quick hand pits in the top 1-2ft as you’re travelling to determine whether any layers easily fail. Loose snow avalanches are also a possibility in steep areas, which will probably stay small but may surprise you if they catch up with you as you’re making your way down a slope.  Steer around slopes steeper than 35 degrees, and be more cautious if you notice wind-loaded snow nearby, by possibly avoiding terrain beneath large wind loaded slopes as well.

    (2/17/2021) Bearpaw area, D2 Wind Slab, NE aspect at 5500ft. Photo: Patrick Kennedy

Avalanche Discussion

The mid-January persistent weak layer is no longer listed as an avalanche problem, as we haven’t seen any avalanches on that layer in over 2 weeks. We are continuing to track it and search for lingering weakness. NWAC observers travelled into the Glacier Creek area on Saturday and found the layer buried 210cm down. Rounding facets were visible, although not the predominant grain form. Keep this layer in mind if you are travelling into upper elevation large windswept terrain where the layer might be buried shallower. This is where it may still contain weaker grains that are closer to the surface and easier for you to trigger an avalanche on.  

Snow showers are continuing in the coming days, and an abrupt warming will occur on Sunday. We will keep seeing avalanches in the new snow layers as snowfall continues. Tree well and deep snow immersion hazards are a serious problem with all our recent snow. Find out more information about deep snow safety HERE.

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