Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

A large storm is winding down, and at mid and upper elevations we received several feet of new snow, and natural avalanche activity probably occurred on Sunday. Continue giving the snowpack time, and avoid all steep slopes on Monday. If you have any doubt, avoid traveling on lower-angle terrain beneath large, steep open slopes as well. 

Avalanche problems

  • Storm Slabs

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

    Snow conditions are extremely variable on both a slope-to-slope scale and throughout the zone right now. In most areas of the zone, it's likely that you could trigger a large storm slab avalanche that could kill you on Monday. Storm slabs may entail non-wind-affected snow or wind-affected surfaces. There are also a few persistent weak layers we've been watching closely, and there's a very small chance you could trigger an avalanche that could fail 1-2ft beneath the new storm layer on one of those layers as well.

    Using tests like hand pits and small test slopes probably won't work well at finding weak layers with the amount of snow we just received. Even standard pit tests might not identify storm weaknesses very well. Any failure planes may not be obvious until you get out on a slope and trigger an avalanche- so avoid all slopes greater than 30°. If you see any red flags like avalanches that came from the tail-end of this storm, or notice any whumphing, or if you have any doubt, it wouldn't be a bad idea to avoid traveling beneath large avalanche paths as well, especially if you make your way towards upper elevations. 

    Example photo: Large, dangerous storm slabs, like this one, are likely to fail with a human trigger on Monday. Avoid steep slopes. 

Avalanche Discussion

Precipitation amounts varied extensively depending on where you are in the zone. Further south, Skookum Creek telemetry reported over 3 inches of precipitation, yet locations on the northerly end of the zone reported closer to 1 inch. Avalanche conditions likely vary as much as precipitation amounts vary in the zone. On Sunday it rained up to almost 4000ft before transitioning to snow. Snowlines will drop considerably Sunday night. Temperatures will be cold on Monday and for the next couple days. 

We've been keeping tabs on weak layers that exist in our snowpack from the last few weeks. Above the solid Early February Crust, weak snow may exist. It's predominantly on upper-elevation slopes that aren't south-facing. In some locations, we've found that it's rounding and becoming less reactive, while in other areas it still propagates in pit tests. This layer is probably 1-2ft beneath the new snow layer, so an avalanche failing on it would be several feet deep. Surface hoar from Wednesday and Thursday may exist on some shady slopes, beneath the new snow layer, as well. Any avalanches that break on any of these persistent weak layers will likely surprise you by failing deeper and/or propagating further than you would normally expect.

In non wind-affected areas, you may trigger or see natural dry loose avalanches on steep slopes. If the sun pokes out, very small wet or dry loose avalanches might occur. Right now there's enough uncertainty in the snowpack that this isn't the time to get out any steep slopes. Stick to lower-angle terrain on Monday. If you get out, please share what you saw with us by submitting an observation. 

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