Bulletin d’avalanche

Mount Shasta

Mount Shasta 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 last year. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Intense wind loading and over two feet of new snow are testing weak layers in the snowpack. This makes for dangerous avalanche conditions near and above treeline. You could trigger an avalanche large enough to bury you on any slope steeper than 30°. Increase your margin of safety today by choosing low angle terrain and watching for blowing snow, shooting cracks, and collapsing. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–3

    Several days of snowfall and powerful southwest wind make this our primary avalanche problem today. Over the past 24 hours, wind speeds averaged 20 mph near treeline with gusts up to 49 mph. Wind speeds will be lesser today but still have enough strength to transport snow near and above the treeline. 

    You'll be most likely to find these wind slabs on predominately north, northeast, east, and southeast aspects. With that being said, the leeward side of trees and other terrain features are catchment areas, so you could encounter a wind slab on any side of the compass in complex terrain. 

    With multiple feet of new snow and consistent southwest wind, an avalanche today could be several feet deep and may not be survivable.

    Avoid traveling on any of the shaded aspects of the compass rose and keep an eye out for drifting, shooting cracks, and collapsing.

    (3/14/2025)

    Wind slab avalanche crown and flank initiated by cornice failure on an east aspect of Gray Butte

    Photo: Mount Shasta Avalanche Center

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2.5

    Over two feet of new snow has fallen below and near treeline across the forecast area. The first half of the snowfall came in cold and dry. Then, yesterday's warm and wet snow came in and capped the cold, less dense snow with a firm slab. This is what we call an upside-down snow structure.

    The likelihood of triggering one is on the decline but still possible. These slabs could be reactive to the weight of a rider, and if triggered, could fail large enough to bury a person. Avoid travel on slopes greater than 30° and watch for signs of instability: natural avalanches, cracking, and/or collapsing. 

    (1/20/2024)

    Soft Slab Avalanche

    Photo: Samuel Clairmont

Avalanche Discussion

Snowfall is tapering off, and wind speeds are on the downward trend. With this, avalanche hazard is decreasing, though the snowpack has just undergone massive change. Tread carefully out there in the backcountry today as weak layers need time to heal. Check your slope angles, look for areas of wind loaded snow, and don't let trees give you a false sense of security. 

The weak layers of graupel and facets that were buried on March 12th are still present in the snowpack but are becoming less and less of a concern. They are now buried over one meter deep, have not produced avalanches, and are unreactive to stability tests.

Travel in the steeps today will be dangerous and we do not recommend it. If you must go, bring an experienced partner and avoid being on, near, or beneath steep slopes greater than 30°. 

We try, but we can't be everywhere at once. If you get out in the woods, please submit your findings on our public observation page.

The Everitt Memorial Highway and Castle Lake Road is CLOSED. For further road information: https://www.co.siskiyou.ca.us/publicworks/page/closures-and-delays

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