Avalanche forecast

East Slopes Central

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You may be able to trigger avalanches in new and lingering wind drifted slabs of snow. A dusting of fresh snow may hide wind textured surfaces. Instead, feel for harder snow layers over softer layers to identify wind affected terrain and steer around steep terrain where you find these stiff snow drifts. 

Avalanche problems

  • Wind Slabs

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

    While the East Central zone did not receive much new snow on Tuesday night, the winds were impressive. Mission Ridge had a gust of 109mph! Shallow wind slabs likely formed on all aspects as terrain features funneled these extreme winds in all directions. You may also find them mid-slope, further from ridges, and in areas you may typically consider sheltered. New snow depths are highest in areas near the Cascades Crest, and avalanches in these areas may be larger. While these slabs are likely gaining strength, it may still be possible to trigger shallow wind slabs on Thursday. Avalanches may run on the recent freezing rain or sleet crust from Christmas, and travel further than you may anticipate. Recent snow, winds, and slick, old snow surfaces are a perfect setup for avalanches. A dusting of new snow on Thursday may obscure wind-textured surfaces. Instead, use your probe or ski pole to feel for stiff wind-driven snow over softer snow to identify areas where wind slabs exist. Shooting cracks and hollow sounding pillows of snow are also signs of wind slabs. Steer around these deeper drifts of snow in steep terrain. 

    (12/21/2022)

    Example of shooting cracks that are a sign of unstable wind slabs

    Photo: Joe Dellaporta

Avalanche Discussion

We have been on a wild weather ride for the last few days, and the powerful winds continued to complicate the snowpack. Times of rapidly changing and active weather limit our ability to gather information on a broad spatial scale throughout the area. But the snowpack is likely very different from a week ago. Observers in the Icicle Creek area found the thin freezing rain crust up to around 5000ft, with just an inch or so of new snow on the surface. Areas near the crest may have significantly more snow overlaying this Christmas crust. At higher elevations, precipitation could have fallen as rain. While a crust still likely exists, it may be more opaque and look less like the clear ice now common in many lower elevation locations. 

On Tuesday near Salmon La Sac, I found significant dry snow below the crust and a well-preserved layer of buried surface hoar in the snowpack. This persistent weak layer showed the potential for initiation and propagation in snowpack tests. Triggering this layer is unlikely because it is below the very thick freezing rain Christmas crust. However, there may be isolated pockets of terrain where a large trigger, such as a snowmobile, could initiate an avalanche on this layer. Therefore, it's worth digging down to look for this thin grey line of feathery surface hoar in the snowpack before committing to steep terrain in sheltered gullies or near rocks and cliffs. 

If you take advantage of some time off work and get out into the mountains, help us out by sending in an observation!

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