Avalanche forecast

Mt Hood

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

A fresh round of low-density snowfall combines with wind to increase your risk of triggering rapidly building fresh drifts. Cracking, active snow transport, and easy hand shears confirm the problem on steep lee slopes. Large and overhanging cornices threaten to trigger these same wind-loaded slopes and may break further back than you expect.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    In this cold, snowy pattern, cornices keep growing until they become unstable and break—then the cycle repeats. Car-sized chunks have broken off in recent days, endangering anything on the slopes below, so choose routes well away from potential cornice fall paths. 

    As you travel along ridgelines, it can be difficult to tell how far back they may break off. Therefore, give them extra space along the ridgelines. Try to find a safe point, such as a tree or large rock, if you need to get a look at the terrain below them. 

    Example: Sharp looking corncies along Pea Gravel Ridge. 

    Photo: Joe Dellaporta

  • Wind Slabs

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

    The anticipated 4-8" of snowfall combined with moderate winds throughout the system will lead to deteriorating avalanche conditions at middle and upper elevations as the day progresses. With the soft snow easy to redistribute, it won't take much new snow to generate significant slabs. By the afternoon, small or large avalanches are likely to be widespread at upper elevations. Recent wind slabs have been cold and have broken apart easily. Marginally warmer temperatures or the fact that these slabs are building above first-density snow might make these slabs more reactive on Saturday. Avoid actively wind-loading start zones, larger convexities, and slopes beneath building cornices. As the slabs build in size and distribution, take a step back and close off rather than open up terrain. Shooting cracks and firm or punchy snow layering confirm the problem.

     

    Example: Strong winds near ridgelines on Mt Hood redistributed shallow amounts of new snow into 1-2 ft slabs!

    Photo: Northwest Avalanche Center

Avalanche Discussion

There's one more problem you're likely to encounter in steep, wind-sheltered terrain: Dry Loose "sluff" avalanches. Mt. Hood Meadows weather station has picked up 2 feet of snow and 2.5 inches of snow water equivalent. The storm cycle started warm, but recent waves of precipitation have been very cold and low-density; the last round delivered 8-12" of cold smoke in the 24 hours ending Thursday morning. Riding conditions remain high quality, with right-side-up density profiles in sheltered terrain. Small dry loose avalanches may continue to run with you on slopes approaching 40 degrees. While these avalanches generally aren't very concerning on their own, they could push you into terrain obstacles or into terrain traps such as a creek or gulley, where they increase your risk of hardship.

Mt Hood Meadows pro patrol reported moderate winds at upper elevations transporting significant amounts of soft snow, but clouds moved in before they could access this terrain. They triggered 4-6" soft slabs in upper elevation terrain on Thursday morning. Slabs were less prevalent at middle elevations. On Wednesday, observers at lower elevations near Tom, Dick, and Harry found that slabs generally fell apart and were stubborn with hand shears, suggesting that more cohesion is needed for the slab to become a problem in sheltered terrain. In this area, the observers found 6-12" of generally right-side-up snow above the (January Drought Layer) JDL crust.  On Tuesday, an observer traveling up the Palmer snowfield found plenty of relatively soft snow (4-finger hardness) still available to be transported, even in upper-elevation terrain. 

The  JDL crust varies in thickness and harbors a thick layer of facets just beneath and sometimes above. This facet/crust combo remains worth watching on N-E aspects at middle elevations where the crust is thinner and more fragile. It could be more of an issue on the north side of Mt Hood where weaker surface snow was found prior to the recent storm cycle. If you head to these remote areas, make sure to assess the potential for a weak layer and dial back your terrain selection accordingly.

We haven’t observed any confirmed avalanches on this layer, but early in the storm cycle, we had propagating test results  (observation/ observation) and whumping collapses on northerly aspects near Bennett Pass (observation). 

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