Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

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

Despite the more favorable weather, the snowpack structure is poor, and conditions will be slow to improve. You could still trigger avalanches on deeply buried weak layers. These slides are likely to break widely across terrain, and they can be triggered from a distance and catch you off guard from above. Avoid traveling on or directly under steep open terrain.

Avalanche problems

  • Wind Slabs

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

    Continued winds will drift the new low density snow into stiff, cohesive slabs on leeward features. On Saturday, observers in Ahtanum Meadows reported gusty winds and plumes along ridgetops. You'll typically find these wind slabs downwind side of ridges, below cornices, and under rock and cliff bands. Use visual clues such as blowing snow, sharp cornices, and textured surfaces to help you identify wind-loaded slopes. These slabs will often look rounded, pillow-like, and sometimes sound hollow.

    A wind slab has the potential to step down to older buried weak layer and become a much larger, unsurvivable avalanche. With these complex and overlapping problems, use a conservative mindset and avoid steep wind-loaded terrain. 

    Gusty winds and blowing snow near Darland Mt on Saturday. 

    Photo: Katie Warren

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    This unfortunate persistent slab problem may plague our forecast and force our terrain selection to low-angle slopes for a while. Weak, faceted snow over the early February Crust is the weak layer responsible for numerous close calls and a fatal avalanche accident near Darland Mountain on Friday. These avalanches are failing 2-4ft deep, propagating widely, and being remotely triggered from low-angle terrain below or adjacent to steep slopes. A smaller avalanche could also step down to this layer. This tricky problem can give inconsistent signs of instability. You may not see any apparent signs of instability before the whole slope fails, and it may not even be the first person on the slope to trigger it. 

    Avoid traveling on or under slopes over 30 degrees. Give steep open slopes wide safety margins. Stay off of and out from underneath steep slopes at elevations above approximately 4500ft, where 1-3ft of new snow has accumulated since 2/24. Little snow exists over this crust at lower elevations, limiting the potential for avalanches.

    (3/1/2024)

    You can trigger similar avalanches on Sunday.

    This remotely triggered avalanche occurred on a North aspect at 6300 ft near Darland Mtn on Friday, March 1st.

Avalanche Discussion

Some moderate winds and a snow shower or two are possible for the East South tomorrow, but overall, it's likely to be a very pleasant day in the mountains. If the sun comes out to stay for a while in the afternoon, you may see some small, wet loose avalanches, rollerballs, and pinwheels. 

Observers across much of the Washington Cascades, particularly the eastern slopes and the West South, have reported numerous large avalanches failing on old snow 2-4 ft below the surface. In addition to the fatal avalanche accident on Darland Mt on March 1st, another large avalanche on an adjacent slope was remotely triggered by a group of snowmobilers. This widely propagating avalanche occurred on a north aspect at 6300 ft. You can check out the observation here. NWAC forecasters visiting the accident site also reported this separate large avalanche (avalanche observation). These all likely failed on the Early February Crust. 

This pattern of persistent slab problems can be incredibly challenging for backcountry decision-making. It takes extremely conservative terrain management and patience. This winter's lower-than-average snowfall and warmer-than-average temperatures contribute to a shallow snowpack prone to developing these tricky weak layers. The issue is especially apparent in the eastern Cascades, which, on a typical year, is already a bit shallower and weaker than areas west of the crest. So, if you're venturing into these eastern zones this winter, be prepared to take a step back in your typical terrain selection and understanding of the snowpack. It's easy to be surprised in these conditions, so with the increased complexity of the snowpack, choose low-angle terrain to enjoy the fresh snow. 

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