Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

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

You could trigger avalanches on a layer of weak snow buried just below the recent storm snow. Be suspicious of steep northern terrain with sparse trees and vegetation, particularly where the wind has drifted snow into deeper slabs. You should approach new terrain cautiously and use small, inconsequential test slopes to see how the snow reacts. If you see shooting cracks, feel the snowpack collapse, or the test slope produces a mini avalanche, you should stick to lower angle terrain. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    We have limited direct observations from the East South zone. However, in all the zones surrounding East South, large avalanches have run on recently buried surface hoar or deeper weak, sugary facets from Mid-November. During avalanche mitigation efforts, Crystal Mountain and Mission Ridge produced avalanches that ran near the ground on the Mid-November facets. We suspect a skier triggered avalanche near White Pass ran on recently buried surface hoar (12/8). Even without direct observations, it's highly likely that similar snowpack and avalanche conditions exist in East South. We have significant uncertainty about the distribution and reactivity of these weak layers, so assessing the snowpack is essential before committing to steep slopes. Approach new terrain slowly and assess conditions as you ascend in elevation. Steep, northerly aspects are the most suspect location for these deeply buried weak layers to exist. Be particularly suspect of steep open terrain below ridges, areas with stiff wind drifted snow, steep rolls in the middle of slopes, and near rocks or cliffs where you are more likely to trigger these avalanches.

    Dig down and identify sugary, faceted layers or feathery surface hoar layers buried in the snowpack. You can also use small test slopes to see if you can get a slab of snow to move. Stay on lower angle slopes if you find the overlaying snow slides easily on these layers, experience whumping collapses, or observe cracks shooting out from your equipment. 

    (12/10/2022)

    A distant view of the skier-triggered avalanche at White Pass on 12/10. This slide is suspected to have failed on buried surface hoar. 

    Photo: Paul Przybylowicz

Avalanche Discussion

Adjacent zones to the north, south, and west have had avalanches on weak snow buried either just below the recent storm snow or deeply buried near the ground. During avalanche control efforts on Sunday, Crystal Ski Patrol produced a large avalanche that ran down to the ground on weak-faceted snow that formed in mid-November. Mission Ridge ski area also produced avalanches on this same layer during avalanche control on Saturday. Other observations have rolled in from the White Pass area of avalanches on buried surface hoar just below this recent storm snow. While we have limited direct observations from the East South zone, avalanches on this layer are widespread enough to impact the East South Zone. I was out in Ahantum Meadows earlier in December and found a similar structure. While it did not seem reactive in that particular location, we remain suspect of higher elevations and northerly aspects. This uncertainty should make you take a step back and closely evaluate shaded slopes that may harbor this weak snow.  

The sun has been warming southern aspects, and now most sun exposed terrain has a melt freeze crust on the surface. Another sunny day is in the forecast for Tuesday, and snow on steep, southern aspects may get heavy and wet. You could see roller balls or wet snow sliding off steep terrain near rocks or cliffs. Stay out from under cliffs or rock faces that begin to shed snow. 

If you get out into the East-South Zone, tell us what you see by submitting an observation on our public observation platform! These observations play an integral role in producing a quality avalanche forecast but also help the greater backcountry community.

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