Bulletin d’avalanche

West Slopes North

Northwest Avalanche Center
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Danger d’avalanche

Sun
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

You can trigger large, dangerous avalanches in steep terrain on Saturday. Some areas are stabilizing quickly, but check the top couple feet of snow to determine whether there are any reactive layers before exposing yourself to large slopes. Start out on small test slopes, and stick to terrain less than 35 degrees until you determine that the upper snowpack does not harbor dangerous weak layers which could bury you in an avalanche.

Problèmes avalancheux

  • Wind Slabs

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

    Several very large avalanches which failed during the wind and snow event hit Highway 20  again on Thursday. Check out the photo below. This occurred during the height of the storm, but we are not too far out from that yet, so continue to exercise caution in steep terrain and beneath runouts of large avalanche paths.  

    There are a number of underlying layers of concern which slab avalanches could fail on, such as a sun crust from Wednesday’s intense sun on steep southerly slopes, or a layer of graupel in other areas. You may find slabs 6 inches to several feet thick. Previously, strong winds redistributed snow into touchy slabs. These will most likely fail in gullies, beneath rock bands, below cornices (which are getting very large) and under ridgelines. Your added weight makes an avalanche occurring on these steep slopes likely. Search for pillow-like drifted snow deposits and feel for stiffer snow as you travel, and avoid these areas on steep slopes. Dig down a couple feet and investigate whether any layers fail easily.  Start in lower angle terrain and small test slopes before exposing yourself to steeper areas. 

    (2/21/2021) A skier intentionally triggered this slab avalanche in Swift Creek on a NE aspect at 4500ft. Photo: Phil Straub

  • Loose Dry

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

    Loose dry avalanches can occur in steep areas that were sheltered from the wind. Several backcountry users reported loose avalanches in the last couple days in the Mt Baker area. Expect similar conditions as temperatures remain cool and preserve the low-density nature on Saturday. Additionally, clouds may part and loose wet avalanches may run on steep south-facing slopes.Retreat off sunny slopes if you notice the snow getting moist. Stay alert, as loose avalanches may run naturally. Avoid travelling in areas where terrain traps such as cliffs, trees or gullies are present if you think you may encounter one of these avalanches.

    A small loose dry avalanche on a steep slopes.

Avalanche Discussion

Currently there is a lot of varying information in the West North zone. The large avalanche cycle just occurred along Highway 20, yet fewer avalanches were observed in other areas. Make sure to do your homework with properly investigating a slope before jumping onto something steep. As we’ve just received a lot of snow and wind, continue to exercise caution- it’s not open season yet! 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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