Avalanche forecast

East Slopes South

Northwest Avalanche Center
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Avalanche danger

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

There is a lot of uncertainty with this storm, but Sunday will likely be a dangerous day in the mountains. Heavy snow with a changeover to rain is a recipe for avalanches. Make conservative terrain choices and avoid traveling on steep terrain. Rollerballs, rain on dry snow, and natural avalanches are all bullseye information that the snow is unstable. 

Avalanche problems

  • Wet Slabs

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

    At some point overnight or in the early morning hours, snow will change to rain.  There is a lot of uncertainty with the timing of the warmup, the potential for freezing rain, and how much snow will fall before the changeover.  However the storm plays out, wet storm slab avalanches that slide easily on the underlying crust are likely.  These avalanches may be large enough to bury you, and the added weight of the water can make them more destructive than you may anticipate.  While wet slabs may be larger, wet loose avalanches will also be a concern, particularly at lower elevations where the new snow will fall on bare ground. With increased uncertainty, it is essential to dial back your terrain choices.  Choose simple terrain with low-angle slopes to enjoy the stormy weather.  Red flag signs for unstable wet slabs and wet loose avalanches are sinking past your calves in wet snow, rollerballs, and natural wet avalanches. 

    (12/6/2023)

    An example of a small wet slab that ran on the ground.

    Photo: Katie Warren

  • Storm Slabs

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

    Upper elevations may stay as snow, but that doesn't mean the danger will be lower up high. We're just dealing with a different avalanche problem. With over a foot of snow falling on a stout crust, you could easily trigger storm slabs. So, even at upper elevations where the snow is dry, dial back your terrain choices by choosing simple terrain with low-angle slopes.

    Terrain over 35 degrees, convex rolls, and areas exposed to the wind are likely spots to trigger an avalanche. The wind may drift the snow into deeper slabs, so be particularly cautious to avoid steep slopes below ridgelines. Look for warning signs like cracks that shoot away from you or other recent avalanches. You can also use quick hand pits and small, steep test slopes to see how easily the new snow slides on the crust. If it slides off easily, that's a good sign avalanches are likely.

    (12/1/2023)

    Small test slopes like this can be great indicators of unstable storm slabs. 

    Photo: Matt Primomo

Avalanche Discussion

After the temperatures dropped below freezing on Thursday, we have a stout melt-freeze crust on the surface that could make a good sliding layer for the new snow. Recent snow had a poor bond to this crust in the adjacent East Central Zone. A similar setup could exist in East South. As you travel, you should carefully observe how well the new snow bonds to the underlying surface. 

Joe Dellaporta got out into the East South on Saturday. While we had hopes of snowmobiling out of the lower elevation snowparks, there is a lot of bare ground from last weekend's atmospheric river. He did find significantly more snow as you travel west in the zone and get closer to the crest. There was over a foot of snow at 3500ft near the HWY410 closure and just 10 inches further east near Bumping Lake. Ahtanum Meadows Snowpark is bare ground.

The good news is that it began snowing hard in East South around midday on Saturday. Let's hope some of that snow survives this next round of rain. But for the moment, depending on where you go, the chance to hit buried rocks, logs, and other obstacles may still be a significant hazard. 

We don't have much for on-the-ground observations of East South. So, if you're out enjoying the new snow, let us know what you see by submitting an observation.

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