Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

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

A few inches of new snow and strong winds will combine to create a fresh batch of shallow slabs of wind-drifted snow. These newer slabs may camouflage the older, bigger slabs that could break widely if they rest on weak snow 1-2 ft below the snow surface. Blowing snow, recent drifting, and hollow drum-like snow surfaces are all signs that can help you pinpoint nearby wind deposits.

Avalanche problems

  • Wind Slabs

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

    We have a couple of layers of wind slabs that you'll want to think about on Sunday. The first one is the older, larger wind slabs formed from our recent wind event on the 9th. The second is the newly forming shallow slabs you may find as new snow starts falling. Expect these newer wind slabs to be softer and potentially more reactive, especially if they rest on recently buried surface hoar. Any triggered wind slab, especially on shaded terrain (N-E aspects), has the potential to break wider than anticipated if it fails on weak snow or a slick crust 1-2 ft below the surface. 

    Be suspect of terrain features that encourage drifting such as the leeward side of canyons and beneath rock and cliff bands. You may also find these wind slabs on upper mountain terrain features, like in chutes/couloirs and on the breakover of unsupported slopes. High wind speeds may have pushed these slabs further down slope than usual, so don't be surprised if you find stiffer pockets of snow on mid-slope convexities. You can avoid this problem by steering around freshly drifted and textured slopes. Shooting cracks or whumphing collapses are apparent signs of instability that should not be ignored. 

    This widely propagating avalanche occurred in wind-loaded terrain and failed on a layer of buried surface hoar.

    SE, 6300 ft near Timberline. 

    Photo: Joe Dellaporta

Avalanche Discussion

A front on Sunday will bring increasing chances of precipitation as the day progresses. This won't be a big storm by Mt Hood standards, but we should get enough new snow and wind to spike the avalanche danger, especially into the evening hours and into Monday. 

Backcountry travelers enjoyed bluebird conditions and good snow quality above 6000 ft on Saturday. I took advantage of the nice weather to travel on the south side and was surprised to find a widely propagating avalanche in the lower Salmon River Canyon (SE aspect, 6300 ft). This avalanche was pretty shallow (6-12 inches) but propagated surprisingly wide. The crown was partially loaded in, so I suspect it occurred sometime on Friday. In a profile on an adjacent slope, I found the culprit being buried surface hoar 4-6 inches below the snow surface. It was easy to identify with snowpack tests. The forecast team is unsure how widely distributed this weak layer is across the zone, but we suspect the most likely places you may find it will be on shaded slopes above 5000 ft moving forward. Any solar slope will now have a crust from our warm-up on Saturday.

Other observers traveling on the North side of Mt Hood found cold preserved snow and a fresh crop of surface hoar from our cold, clear night on Friday. This wasn't a problem on Saturday, but it could be a future weak layer once new snow starts piling up. 

The lower elevation snowpack has endured a beating after last week's warm-up. Below 5000 ft you'll encounter plenty of shallowly buried objects, open creeks, and rough surfaces. 

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