Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 3 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Heavy precipitation and strong wind speeds will combine to create very dangerous avalanche conditions at upper elevations . Travel in or below avalanche terrain is not recommended. 

 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2

    Human-triggered avalanches are very likely in wind loaded terrain. We have all the ingredients for avalanches failing in wind drifted snow on Friday. Lots of wind, new snow, and a possible weak layer sitting on a slick bed surface. These wind slabs may even avalanche naturally, so it won’t be the day to thread the needle. Give yourself plenty of space and avoid pockets of wind drifted snow. 

    You’ll typically find these slabs forming on the downwind side of ridges, below cornices, and under cliff & rock bands. You can use visual clues such as blowing snow or looking for dunes at the snow surface to help you identify slopes of concern. Shooting cracks under your skis/split/sled/feet are direct signs telling you that you found an unstable slab of drifted snow. 

    Friday will be a good day to steer clear and avoid traveling on and under steep wind loaded slopes. 

    Shooting cracks like this are obvious signs of unstable snow. 

    Photo: Joe Dellaporta

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    You may be able to trigger avalanches within the new storm snow as new snow stacks up. New snow will be falling on a slick bed surface at these elevations, so it may be easy for you to trigger avalanches failing on this crust. Any slopes above 35 degrees should be considered suspect. As you travel, use small test slopes and quick hand pits to gauge how sensitive the new snow is. It won’t be a bad day to just consider avoiding all steeper ( >35 degree) terrain. 

     

    (12/20/2022)

    An example of a small storm slab. 

    Photo: Public Observation

Avalanche Discussion

Don't overthink it, Friday is shaping up to be a dangerous day.  If I were you, I would take a step back and let the storm run its course. Mt Hood is forecast to receive over 1’ of precipitation by the end of the day accompanied by very strong west winds. The red flags will likely be in your face at the trailhead. All these in-your-face signs should help keep your terrain selection simple.

On Thursday I went out searching for graupel and wind slabs in Pea Gravel Ridge area. I was successful at finding both. Below treeline, I was easily identifying the graupel sitting above a slick crust. Once at ridgetop, I observed moderate wind speeds, active drifting, and sensitive wind drifted snow. These wind drifted slabs were easy to trigger and failed 6-12 in deep on a layer of graupel sitting above the crust. These slabs were generally small, but are certainly building in size as strong winds drift new snow. You can read my full observation here. 

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