Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

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

A spring storm will bring snow and wind to the East South, and you could trigger avalanches in fresh wind-drifted snow. Steer around steep slopes where you observe stiff textured snow or deep pillow-like drifts. While the likelihood is low, large triggers, such as smaller avalanches, could initiate a much larger avalanche on deeper weak layers at upper elevations. 

Avalanche problems

  • Wind Slabs

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

    At mid and upper elevations, moderate winds and a few inches of new snow may form shallow fresh wind slabs where you could trigger an avalanche. Expect more snow and larger avalanches further west, towards the Cascade Crest. Slopes below ridgelines and the base of cliffs are likely spots for wind slabs to form. Look for textured surfaces or stiff, hollow-sounding snow to identify wind slab locations. You can also use quick hand pits, your probe, or poles to feel for stiffer snow over softer snow. If you see shooting cracks in wind-stiffened snow, this is a sign to choose low-angle terrain. 

    At mid-elevations, wet loose avalanches may become increasingly likely in the late afternoon, and the rain/snow line creeps up to elevations with more recent snow. 

    Cornice falls are common this time of year and are a hazard on their own, but they can also trigger slab avalanches on the slopes below. Don't linger for long beneath these monsters. We expect most of these avalanches to be small, but there is potential for small wind slabs to step down into deeper layers and become large. 

    (2/28/2023)

    Look for pillow-like slabs and wind-textured snow to help you identify slopes of concern. 

    Photo: Katie Warren

  • Persistent Slabs

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

    We think the potential for very large persistent slab avalanches is isolated, but there may still be slopes where this problem lurks. While the likelihood is low, the consequences of triggering a 2-4ft thick avalanche could be dire. You'll want to consider these risks before jumping into steep north-facing terrain at upper elevations. Triggering a small wind slab or cornice fall could result in one of these much more dangerous avalanches. If you travel in this terrain, choose well-supported slopes and avoid likely trigger points like shallow spots near rocks and trees or steep convex rollovers. 

    We have observed a preserved weak snowpack structure of faceted snow over the Early February Crust on some northern aspects above about 5500ft. Stability test results are inconsistent, and this layer has had little avalanche activity since the warm-up. We can't write this tricky problem off yet, but we're gaining confidence that it's much more difficult to trigger. 

    These avalanches can surprise you by propagating widely or being triggered from a distance. You may or may not receive signs of instability before triggering this type of avalanche. The best way to reduce your risk of triggering persistent slabs is by avoiding leeward sides of ridges and steep, rocky, complex start zones on the north side of the compass. 

    (3/6/2024)

    Steep, shady, wind-loaded terrain is the type of terrain that the persistent problem could plague. 

    Photo: Anthony Lubetski

Avalanche Discussion

Areas closer to the Cascade Crest near White Pass and Chinook Pass picked up around 3-4" of snow on Monday night and Tuesday. Wednesday's storm will bring additional snow to the East South and likely push precipitation much farther east in the zone. You can expect anywhere from 5-7" of snow to fall during the day on Wednesday along with moderate winds. With the recent clear nights and warm days, there may be slick or weak snow surfaces. So check the bond with the old snow surface frequently as you travel. If you find the new snow slides easily, avalanches are more likely.

This isn't a particularly cold storm, and freezing levels will increase throughout the day. So, you may find some wet snow avalanches at low and mid elevations as the day warms up. The diurnal warming and dynamic spring weather can lead to rapidly changing avalanche conditions. New snow concerns like wind and storm slabs can quickly become wet snow problems in the afternoon. Make frequent observations, and be prepared for changing conditions and snow stability. 

I was in the Ahtanum/Darland Mt area last Tuesday. The prolonged period of sun and warm temperatures had done a number on the lower elevation snowpack and steeper southerly slopes. The snowpack on southerly aspects was wet and moist to the ground but more supportable than other sunny aspects where you could punch through wet snow to your waist. Northerly aspects held a colder, more layered snowpack, with preserved weak snow over the early February crust about 4' down on a north aspect @ 6700'.

Observations have been sparse. Help create a more accurate forecast by submitting your public observations here. 

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