Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

 An avalanche could fail with your added weight on a deeply buried weak layer in isolated areas. They are getting more difficult to trigger, but if you do trigger one, expect catastrophic results and you will most likely die. Assess the weak layer with a snow pit before considering exposing yourself to open slopes greater than 35 degrees.

Avalanche problems

  • Deep Persistent Slabs

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

    You could trigger an avalanche on a deep persistent layer which is buried 3-5 feet down. The layer is progressively more difficult to trigger as time passes. At the depth this layer is buried, it is unclear whether the sole weight of a person would cause an avalanche unless they found a shallower spot, which is possible. A snowmobile could easily trigger it at that depth. If an avalanche does occur, it will be very large and you will probably not survive. 

    For this avalanche problem, there are no obvious signs of instability like you might find with other problems. You need to dig down to the Jan 13 crust and make note of the layer above it, observing the presence of persistent grains and how readily that layer fails. Broad open slopes and large features in areas steeper than 35 degrees is where you are most likely to find the weakness, so avoid those slopes unless you have investigated the strength of the weak layer. If you must get on steep slopes, your best option is to travel on slopes that you already know slid on that layer.

    (2/11/2021) A very large natural slab avalanche which wrapped around the entire cirque on the west facing slope of 3 Fingers in the Mountain Loop area, most likely failing on the persistent weak layer from mid January. Approx 6300ft start zones.

Avalanche Discussion

Stay alert for any other small avalanches which might occur in the top few inches of snow.  Triggering  loose dry avalanches or small slabs at higher elevations may occur.  They might catch you and take you for a ride, or could add enough weight to trigger the deeper slab, resulting in a very large avalanche.

Unfortunately, a snowbiker triggered an avalanche on the deep persistent layer in the East Central zone on Monday, and was buried and killed. The Accident Reports page provides more details about the incident. You can also see the short video about it in the media gallery below. Avalanches failed on this layer in nearly all of the forecast zones in the Cascades in the last 2 weeks, and a number of them involved people. Recently the avalanche count has slowed, but the layer is still lurking.  Make your decision to travel out on a steep slope based on solid evidence, because the risk versus reward is not worth the consequence of not making it home at night.

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