Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
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Danger d’avalanche

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

Points saillants

Strong winds and heavy precipitation will combine to create very dangerous avalanche conditions at mid and upper elevations. Avoid all areas where avalanches can start, run, or stop. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1.5–2.5

    The west winds will be raging and snowfall rates will be intense, so the most dangerous conditions will be in specific areas of wind drifted snow. These wind drifted slabs are expected to be touchy, large, and potentially deadly if triggered.

    You’ll typically find these slabs on the leeward side of ridges & canyons, below cornices, and under rock/cliff bands. Blowing snow should be quite obvious, so paying attention to where the wind is depositing snow should help you identify slopes of concern. Also, be on the lookout and steer around locations that hold stiffer pockets of snow or pillow-like slabs at the surface. Don’t pull the avalanche dragon's tail any harder if you notice shooting cracks under your feet or machine as these are obvious signs of instability. So your best bet will be to simply avoid traveling on or under locations that hold wind drifted snow.

    (3/23/2023)

    Blowing snow and sharp cornices will help you identify problematic slopes. Avoid slopes on the right side of this photo. 

    Photo: Joe Dellaporta

  • Storm Slabs

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

    In more sheltered areas, any steep slope should be considered suspect. As new snow piles up it may be easy for you to trigger avalanches failing within the new snow. These slabs may be touchy and easily triggered especially during periods of heavy snowfall. Natural and human-triggered slides are expected in terrain 35 degrees and steeper, especially on unsupported slopes and convex rollovers. Give the new snow time to settle and stabilize before pushing into steeper terrain.

    (12/20/2022)

    An example of a small storm slab. 

    Photo: Public Observation

Avalanche Discussion

Mt Hood will be getting the lion's share of precipitation out of this storm. So don’t overthink it, Saturday is shaping up to be a very dangerous day in the mountains.

Leading up to this storm most aspects (besides northerlies) below 6000 ft held  a melt-freeze crust at the surface. In some locations observers even noted graupel resting on this crust. The question now will be how the new snow bonds with these variable surfaces. Initially, it may not bond well, especially in areas where graupel sits on the crust. The best strategy will be to let the storm run its course and choose sheltered terrain less than 35 degrees. 

Last week observers reported weak snow associated with a crust that sits 2-3 feet below the snow surface. This layer was likely responsible for the isolated whumphs in the Gunsight Ridge area and propagating results( observation) near Vista Ridge. While isolated and unlikely, I’d still keep this information in mind especially if you find yourself traveling on higher elevation, northerly aspects. 

 

Régions couvertes