Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Large slopes will be dangerous and highly consequential on Tuesday. It will be easy to trigger a shallow slab that could take you for a ride in a fresh wind drift. However, the threat of a stubborn 5 to 15 ft thick hard slab releasing on a steep, unsupported slope makes conservative terrain a wise choice.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Tuesday's wind slab setup concerns us because it may be easy to trigger a shallow soft slab, but you could also trigger a deeper hard slab overlying softer snow and sitting on a crust. Intense WNW winds stripped snow off of many aspects on Mt Hood through Monday, loading multiple slopes above treeline to the breaking point. Mt Hood Meadows Patrol reported multiple small and one large natural avalanche that released with strong wind transport Sunday night into Monday morning. Other observers witnessed a large natural slab release on the upper mountain, serving as a reminder that even more dangerous conditions may exist higher on the mountain. While the potential for natural avalanches may be limited to the upper mountain, another 4-6" of snow will create reactive slabs that you can easily trigger on a wind-loaded slope steeper than 35 degrees in the morning. By the afternoon, settlement and the impact of the sun may limit these soft slab avalanches to the E and N sides of the compass. The potential for a hard slab release means that professionals would give a wide berth to large open slopes and terrain rollovers that have been wind loaded during this storm cycle. Slabs could be 5-15 ft thick and may run a long distance on the 3/21 bed surface. Cornice fall would be an easy way to trigger an avalanche on the slope below although a human trigger is not out of the question. Given the consequences, stick to smaller terrain features where you can control the scale of the problem. Avoid actively loading slopes and areas where you experience propagating cracks or pillow-like drifts. Anticipate wind loading on the E sides of canyons and wind loading may extend down to valley bottoms. If you're not sure how thick the slab may be in your terrain, seek wind-sheltered terrain (where you will find the best riding conditions) and low-angle slopes. Storm slab activity should have trended downward by Tuesday, but it's a good idea to test the snow in the upper 2 ft of the snowpack, even in wind-sheltered terrain. Winds formed slabs below treeline and in isolated areas, you may find wind drifts that you can trigger below treeline, but in general, we expect these elevations to be healing quickly by Tuesday.

    (4/3/2023)

    Small natural avalanches that ran Sunday night or Monday morning in heavily wind-affected snow. Areas of wind-textured snow will be primed for human-triggered avalanches on Tuesday.

    Photo: Mt Hood Meadows Pro Patrol

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Temperatures will be cool, but with winds decreasing and increased sunshine, expect wet loose activity to spread onto more aspects on Tuesday. These avalanches will likely be small and manageable on their own but they can pose a hazard around terrain traps like cliff bands, steep trees, or gullies.  If Monday's thin crust breaking down, rollerballs start moving downslope, or you experience wet/sticky snow it's time to adjust your aspect and limit your exposure from above. While most of these should be small, there's plenty of snow to entrain and the depth of entrainment is primarily limited by how warm the snow surface becomes.

    Don't forget about dry the potential for fast-running dry loose avalanches on cooler and shady aspects. These could take you for a ride that could end poorly in tight trees or above rocks or cliffs. 

    Example: Wet Loose avalanche on a steep sunny slope. Note how it originated at a point, near trees and rocks.

    Photo: Dallas Glass

Avalanche Discussion

Intense winds put a damper on the unseasonably good riding conditions experienced over the weekend. They also continue to maintain more dangerous conditions even as the snowfall rates decrease. Mt Hood Meadows picked up 7" since Sunday night. Without factoring in settlement, this storm cycle has delivered approximately 55-60" of snow. The snow continues to settle approximately 6" per day, despite the cold temperatures. We've had some close calls with deep snow safety across the region during this storm cycle and the situation is particularly acute in the Mt Hood backcountry where a backcountry traveler was able to rescue his partner from a hole above a creek near Pea Gravel Ridge.  Please practice deep snow safety and keep your partner in sight until the new snow settles. 

In addition to the natural avalanches previously mentioned, Mt Hood Meadows found a reactive wind slab layer 12-16" down on Monday. Mt Hood Meadows Patrol has reported a variety of avalanche activity from control work throughout the storm cycle.

Observers on Gunsight ridge on Sunday around 2 ft of snow above and well bonded to the 3/31 crust. Cold snow remained even at low elevations on N and E aspects with a subtle mid-storm interface 6" down. Sunshine in some parts of the mountain may produce crusts by Tuesday on most aspects below 4500 ft. This may extend up to higher elevations on steep S or W-facing slopes.

Leading up to this storm most aspects (besides northerlies) below 6000 ft held a melt-freeze crust at the surface. In some locations observers even noted graupel resting on this crust. 

Last week observers reported weak snow associated with a crust that sits several feet below the snow surface. This layer was likely responsible for the isolated whumphs in the Gunsight Ridge area and propagating results( observation) near Vista Ridge. While isolated and unlikely, keep this information in mind especially if you find yourself traveling on higher elevation, northerly aspects.

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