Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

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

Forecast updated 0723 to include a wind slab problem due to reports of significant wind drifts above treeline.

Wind slabs continue to build on a variety of aspects at upper elevations and could be large enough to ruin your day in isolated locations. You can also trigger small wet avalanches at any elevation, but fresh snowfall will create a small shedding cycle above treeline. Adjust your aspect and choose lower-angle terrain if you see rollerballs forming.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    During the most recent storm, significant amounts of precipitation fell as snow above 6500 or 7000 ft. Moderate W and WSW winds gusting strong during Thursday's storm produced some slabs with fresh slabs forming as NNW winds stronger than forecast drift additional snow early Friday. Colder shaded aspects at upper elevation will maintain the threat of slabs longer as temperatures rise above freezing in most areas. As you transition into winter-like conditions, use a pole or probe to consistently monitor the depth of new snow over the crust. Rain rills texture the landscape. As drifts increase in size and you suspect wind-loaded slopes might have 6" drifts, steer around slopes steeper than 35 degrees.

    Example: Fresh, sharp cornices can indicate a potential wind slab on steep slopes below.

    Photo: Andrew Kiefer

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    You may encounter two varieties of wet loose avalanches on Friday: (1) At upper elevations, several inches of dry snow fell and drifted more deeply in places. Friday's warming temperatures and increasing sunshine will create rollerballs and a cycle of shallow avalanches as the sun moves around the dial. These small avalanches will be most consequential where snow has accumulated more deeply and above terrain traps. (2) Near and below the treeline, saturated upper snowpacks will be soft and slushy once the crusts break down. Note this transition. Once it occurs, you can trigger a small avalanche on a slope steeper than 35 degrees. 

    Example: Wet loose avalanches.

    Photo: Public Observation

Avalanche Discussion

While wind slabs lurk in upper-elevation terrain, most elevations look like April as cracks open up and pull away from rocky outcrops. Following an expected overnight freeze Thursday night, a return to unseasonably mild January weather will renew the wet avalanche problems. In addition to small wet loose avalanches, anticipate the potential for isolated glide avalanches. Note the locations of existing large open cracks and limit your time below similar terrain features and anywhere smooth bedrock exists underneath the snowpack. Glide avalanches take the entire snowpack with them and with over 80" of snow on the ground, they could be quite large. Sagging cornices that have not yet failed may do so. Limit your time on or below these slopes as well.

Mt. Hood picked up 1.5-1.75" of water equivalent in the last 24 hours; most of that water fell as rain. Our highest observations on Thursday were from 6000 ft at Mt. Hood meadows where patrol noted rain transitioned to a mix of freezing rain and snow during the day. We suspect the rain/snow line extended up to at least 7000 ft during peak warming Wednesday night. MHM Pro Patrol also noted no natural wet avalanche activity, but boot penetration was 12-18". Glide cracks are widespread in the terrain, but so far glide avalanches have been rare. Rain rills texture the landscape. Temperatures have predominantly been above freezing over the last 10 days at Mt. Hood and the snowpack seems well set up to handle more mild temperatures.

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