Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

Wind-drifted snow slabs at upper elevations are where you are most likely to trigger an avalanche on Wednesday. These dry snow drifts of heavier, and thicker wind-affected snow may extend down into the mid elevation band. Search out wind-drifted deposits and avoid them on steep slopes. 

Avalanche problems

  • Wind Slabs

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

    Thick, large slabs deposited in unusual locations exist at upper elevations and possibly the upper reaches of mid-elevations. It's possible that the weight of a human could trigger an avalanche on one of these wind slabs. The slabs formed just over a day ago with strong wind, so they may be found lower on a slope or drifted into unusual areas.

    We're not quite sure how reactive these slabs may be, and we have limited information from upper elevations. Be prepared to evaluate conditions for yourself if you make it this high. Due to to intensity of the winds, the slabs could be quite firm. You might not find yourself sinking into them at all. Just because surfaces may be relatively hard, it's not a guarantee that you couldn't find a spot where you could trigger an avalanche. Dig down to underlying layers and evaluate the bond beneath the new snow layer. If a stiffer slab is sitting over a softer layer of snow you might be able to trigger an avalanche.

    A couple inches of snow may fall during the day Wednesday. It'll still be windy, but this new layer could disguise underlying slabs, or could form newer and more reactive shallow slabs. When you find more than about 6" of dry snow over underlying layers, start on small slopes before stepping out onto larger ones. When in doubt, steer clear of wind-loaded slopes steeper than 30°. 

    Example photo: Wind drifted snow, obvious in the ripples. The snow deposited in the gullies, which is where avalanches occurred. 

    Photo: Lee Lazzara

Avalanche Discussion

Rollerballs and small amounts of wet loose activity may occur. It will probably happen around the rain/snow line vicinity. If you see rollerballs or small wet slides coming down, avoid steep nearby slopes. 

The Christmas storm dropped just over an inch of water since midday on the 25th and through much of the night. Wind was strong. Snowline started around 3000' but even at 5000' only a few inches of snow accumulated near the end of the storm. We aren't exactly sure of the elevation where there was remarkably more snow, but we suspect it's somewhere in the vicinity of the transition between mid and upper elevation bands.  At some higher elevation, probably above at least 6000ft or so, the storm equated to about a foot of highly wind-affected snow. 

Before the Christmas storm, around 6 inches of wind affected snow exists from the previous week at mid and upper elevations. Beneath that layer, a crust exists. From there to the ground, snow layers are moist with varying crusts, from about 5500ft and lower. We don't expect avalanche activity to occur beneath the crust in areas where the crust hasn't been completely softened by the warm temperatures and rain. 

As is the trend for this year, beware of early-season hazards like shallowly buried rocks and roots, and open creeks. Don't forget there's an extremely variable crust under the new snow layers, and it may be exposed in some locations due to the extreme wind. Snow at mid and lower elevations will likely be punchy, possibly down to the ground, if you're on foot. If you make it out, especially to upper elevations, we'd love to hear from you! Please submit an observation using THIS link, or better yet, use our app, Avy. 

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