Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Forecast updated 7:20 AM to reflect more snowfall at upper elevations, creating widespread stiff wind slabs. Shifting winds will create erratic loading patterns, so assume these slabs could exist on any aspect. Avoid all steep slopes once you ascend into terrain with drifts 6" or deeper.

Problemi valanghivi

  • Wind Slabs

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

    The forecast has been updated to reflect deeper snowfall at higher elevations on Mt Hood where 8" of snow overlying the 4/11 crust. Slabs may be large, stiff, and could break across an entire terrain feature. It may be difficult to assess which slopes have slabs as winds shift with the passage of a surface low. Keep it simple and avoid all slopes steeper than 35 degrees at upper elevations. Near treeline, you may be able steer around smaller pockets of wind-drifted snow near ridgelines. Any slab 6" or deeper can take you for a ride. At present, any slabs below treeline are expected to be isolated, but maintain vigilance and prepare to navigate around actively or recently wind-loaded slopes if you encounter them.

    Example: Tracks filling in are a good indication that winds are loading steep, lee slopes nearby.

    Photo: Ryan Matz

Avalanche Discussion

Although it snowed much of the day on Tuesday, most of the terrain only accumulated 2-3" of snow as the warm surface from the previously saturated snowpack ate into snowfall totals. The result was that wind slabs were too shallow to be a problem on Tuesday up to around 7000 ft.  By Wednesday with another 2-4" of snow, we expect the hazard to increase.

Keep in mind that the April sun is strong and if we do get sun breaks, expect rollerballs to initiate from trees, rocks, and cliffs in less wind-exposed terrain. Small wet loose avalanches will quickly follow and you can retreat to shaded aspects if there's significant snow to entrain.

Mt Hood Meadows Patrol reported wet natural avalanche activity on steep and cliffy terrain Sunday through Monday night. If you find yourself punching through the 4/11 interface at very low elevations, wet avalanche problems may linger locally and you should limit your exposure to steep terrain. Observations have been more limited at higher elevations, but snow levels reached 9000 ft for an extended period of time, creating saturated snow at all NWAC forecast elevations during the atmospheric river. The shallow dry fresh snow didn't insulate the saturated snowpack very well once temperatures dropped Monday night, enabling the 4/11 interface to refreeze quickly in exposed terrain. Travel may be quite slick in scoured terrain where the crust is exposed on Wednesday. 

On Sunday, Joe Dellaporta explored the Lookout Mountain area on a snow machine. At lower elevations, he found a wet and consolidating snowpack. Unsurprisingly, near the ridgetop at 6000 ft, he found a deeper and more layered snowpack. Photos in the gallery. After the snowpack absorbed about 1.5" of water early this week, this layered snowpack may be starting to transition and if you head out we'd be interested to hear what you find. 

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