Avalanche forecast

East Slopes North

Northwest Avalanche Center
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Avalanche danger

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

On Wednesday, you may be able to trigger small avalanches in freshly fallen snow on slopes 35 degrees and steeper. The most dangerous slopes will be above treeline where avalanches may be bigger and easier to trigger. Watch for recent avalanches or test slopes that slide easily as signs that you should stick to lower-angle terrain.

Avalanche problems

  • Storm Slabs

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

    Storm slab avalanches will be the largest and most dangerous above treeline. You could trigger avalanches within the new snow or at the interface of old and new snow. Storm slabs will be growing throughout the day. If you find unstable snow, stick to lower-angle slopes under 35 degrees. Avoid traveling on convex roll-overs and steep, unsupported slopes. Use extra caution in and around terrain traps, where any avalanche could have serious consequences.

    Expect 8-12" of snow to accumulate by Wednesday evening on Washington Pass with 3-5" in the eastern mountains along the Methow Valley. Above treeline you may encounter drifting and stiffer, wind-affected snow. Cracking in the snow, sculpted drifts, and stiff feeling snow are all indicators. Avoid leeward wind-loaded slopes over 35 degrees. On any slope, you can use quick snow pits and small, inconsequential test slopes to check if the snow slides easily. Look for a potential poor bond at the new/old interface where observers have reported weak surfaces, including surface hoar below 6,000ft. 

    (12/28/2020) An example of a snowboarder-triggered avalanche in recent snow on Shuksan Arm near Mt Baker ski area (NE, 5400ft). Photo: Colin Wiseman

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2

    Persistent slab avalanches are still on our radar due to a weak layer of sugary snow that sits above and below a thin crust from early December. This structure continues to warrant respect, even though the chances of initiating a slide have significantly decreased.  The consequences of triggering avalanches are serious as they could easily bury or kill you. These dangerous and surprising avalanches can catch even the most experienced backcountry travelers. Avoid hanging out, and grouping up in potentially consequential runout zones. This may include sparsely treed slopes or other terrain traps. Watch for obvious signs of instability like whumphing collapses, or cracks shooting through the snow.

    The layer of concern is a thin weak layer of small facets (and in places surface hoar) buried about 2-4 feet below the surface. Near the top of Washington Pass, this weak layer will be sitting on an icy crust. Further east in the zone, the crust has decomposed into a mix of melt forms and weak grains. At lower elevations, there's less concern for triggering this layer.

    (12/23/2020) Persistent slab that likely ran on the Early December Crust. West facing slope in the trees at 6,800ft near Silverstar Mountain.

Avalanche Discussion

On Sunday an observer in Cutthroat drainage found sudden test results within recent storm layers down about 12" and 24" on a northeast aspect at 6,500ft. Storm totals since Christmas are around 3-5" of settled snow. Previous surfaces were a mix of decomposed grains and wind packed particles in some areas, and weak snow over slick bedsurfaces in others. Observers have noted that many slopes ran during the widespread avalanche cycle of December 21st. In some cases, this has allowed folks to cautiously step out and travel onto slopes safely, if they know for certain that it already slid. The new snow may obscure evidence of where these slides have run, creating continued uncertainty. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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