Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

New snow and wind will build fresh, shallow slabs that you can trigger in exposed terrain on Wednesday. Shifting winds will create erratic loading patterns. Steer around steep slopes on either side of the ridgeline, assuming the slope to be wind loaded until you observe evidence to the contrary.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Reactive wind slabs will form in avalanche start zones Tuesday night through Wednesday. In most areas, winds will drift 2-4" of fresh snow lying over 1-2" of snow that's pasted into a very firm crust. The depth of snow over the recent crust will help you anticipate where wind drifts may be deep enough to harm you. Any slab 6" or deeper can take you for a ride. These reactive pockets of snow will be most commonly found just below fresh, sharply corniced ridgelines. If more snow falls than we anticipate; or if the winds blow and drift snow deeper down into the canyons, then anticipate these pockets of reactivity to shift or become more widespread. It may be difficult to evaluate which aspects will have the most wind loading as moderate winds shift direction. Give steep (35+ degrees) or unsupported slopes a bit of extra space if you have uncertainty about the loading patterns. If you find deeper or more widespread drifts, shooting cracks, or more reactive interfaces dial back your terrain selection a notch further.

    Example: Small wind slab triggered on a rollover just below the ridgeline. Small avalanches in similar terrain may be common on Wednesday.

    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. While the avalanches will be mostly small, think about where a small avalanche could get you into trouble above a rocky slope or terrain trap such as a creek or gulley. 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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