Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

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In sintesi

Rising freezing levels and sunshine will thaw the snowpack over the next 24 hours. The potential for wet avalanches will increase throughout the day on steep, sun-exposed slopes. You can also still trigger avalanches in wind drifted snow at upper elevations. Carefully evaluate changing conditions, and switch aspects or head home by the time snow surfaces become wet and unconsolidated.

Problemi valanghivi

  • Loose Wet

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

    Freezing levels are expected to skyrocket to 9000ft on Sunday with another round of sunshine.  Even though many snow surfaces are already wind-battered or rain-affected, wet loose avalanches will be a concern during the heat of the day. These avalanches will likely be small, but it wouldn't be out the question for a few to grow large. Of most concern are slopes greater than 35 degrees facing E-S-W in the near treeline band. A crust formed January 6th sits 6-8in below the surface and could be a good sliding surface for avalanches. If you see roller balls, pinwheels, or snow shedding from rocks and trees, seek out slopes with low consequence away from terrain traps.

    (4/11/2021) An example photo of small wet loose avalanches (D1) you may encounter on Sunday. Photo: Andrew Kiefer

  • Wind Slabs

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

    A fresh crop of wind slabs formed since January 6th,  and sit above a firm crust. They are dense and settling quickly, but could still be reactive to human traffic on unsupported slopes greater than 35 degrees. Cornices also grew during the past week of stormy weather and could fall on slopes below acting as huge triggers. Carefully assess the surface snow using test slopes and hand pits before committing to bigger terrain. If you find shooting cracks or recent avalanches, choose supported slopes sheltered from the wind. 

    In the alpine, at least one very large natural avalanche occurred during the recent storms. Although the likelihood of these avalanches continues to decrease, they should give you pause if you plan to venture high on Mt Hood. 

    (1/8/2022)

    Formations of wind drifted snow like these could indicate wind slabs on nearby slopes (E, 6300ft)

    Photo: Andrew Kiefer

Avalanche Discussion

Skies finally cleared after a 6-day storm brought 5-7+ feet of snow to Mt Hood. A very large avalanche (D3.5) ran naturally over the past 72 hours on the upper Newton Clark Glacier with debris flowing thousands of feet downslope into Newton Canyon. Many large avalanches ran during the storm in wind drifted snow as well, along with reports of natural cornice falls. On Saturday, Mt Hood Meadows Ski Patrol reported avalanches 6-10in thick that were stubborn to trigger with explosives. No cracking was observed, and snowpack tests resulted in resistant planar fractures and no propagation. With rain and fluctuating snow levels during the storms, the snow is dense and quickly gaining strength. Surfaces are a mixed bag with rain rills at lower elevations, 6-12in of wind-affected snow above a crust at mid-elevations, and scoured icy surface and deep wind drifts in the alpine.

The big warm-up Sunday poses a bit of uncertainty, so monitor changing conditions throughout the day. If the avalanche forecast doesn't line up with what you see, and a wet loose cycle really starts to take off, have a backup plan and keep your return routes in mind. In addition, all the low elevation snow will melt significantly. Be heads up around buildings and expect snow to shed off roofs.

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