Bulletin d’avalanche

Summit Lake

Chugach National Forest Avalanche Center
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Danger d’avalanche

Tue
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 7 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Strong winds today will add stress to an already weak snowpack in Summit Lake. Human-triggered avalanches 1 to 3' deep on buried weak layers are likely, and natural avalanches are possible in areas experiencing wind loading. Smaller wind slab avalanches up to 1' deep are also likely today at upper elevations. The snowpack conditions are dangerous in Summit Lake, so we recommend avoiding travel on or under steep slopes.

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Join us Friday, Feb. 13, for the annual Snowball fundraiser! This event is a collaboration with the Alaska Avalanche School and is always a fun way to support two nonprofit organizations that provide avalanche information and education in our area. Silent auction, beverages, hors d'oeuvres, and music by Hope Social Club! Tickets and event info at alaskaavalanche.org

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–3

    Recent avalanches: After the last storm on Thursday, there was a widespread natural avalanche cycle in Summit Lake, ranging from large to very large avalanches (D2 to D3). Recent avalanches were observed on Moose Mtn, Roaring Ridge, Manitoba, Butch, and Raven's Ridge.

    We are back into a warm and wet weather pattern this week. Light precipitation started last night and should continue throughout the day with little accumulation expected. Unfortunately, the rain line is expected to move up to 2000' today and continue to rise towards 2400' tonight. Heavier precipitation is expected overnight tonight through Tuesday afternoon, with up to 6 to 12" of new snow above 3000' (0.5 to 1" of water). Very strong east winds will accompany this wet weather, with averages of 25 to 35 mph expected today, increasing to averages of 50 to 60 mph overnight. 

    The snowpack in Summit Lake is thinner than in our other forecast areas, and therefore, the weak layers are closer to the surface and easier to trigger. We are also still getting large collapses (whumphing) during field outings, which are a clear sign that the snowpack is unstable. Human-triggered avalanches 1 to 3' deep remain likely in this zone, and the added stress of precipitation and strong winds today and tomorrow could produce natural avalanches. 

    The best way to manage this problem is to avoid traveling on or below steep terrain. Be aware that you won't always get those clear warning signs, even though the snowpack is ready to produce a big avalanche. 

  • Wind Slabs

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

    The onset of the wet weather is bringing strong winds along with it. Overnight, east winds averaged 10 to 20 mph, and today the winds should increase to an average of 30 to 40 mph. There is plenty of soft snow on the surface about 2500' from last week's storm that could be blown into fresh wind slabs about 1' deep today. These tend to form along ridgelines, gullies, and convex features in exposed areas. You can identify wind slabs by looking for where snow is being actively transported, using small test slopes to check for shooting cracks or small avalanches, and feeling for hollow pillows of snow that were recently deposited by the wind. Triggering a small wind slab avalanche could be enough to initiate a larger avalanche on a buried weak layer (problem 1).

Régions couvertes