Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

It is likely that you can trigger a storm slab avalanche on Wednesday. Failures could occur 1-2+ feet down in the snowpack. Avoid traveling on slopes steeper than 35 degrees, and consider staying out of areas beneath large avalanche paths as well.

Avalanche problems

  • Storm Slabs

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

    Numerous avalanches occurred in neighboring zones in the last four days. Some failed naturally while others required a trigger, whether a tree bomb or the weight of a person. These avalanches mainly failed one to two feet down. More snow since then could mean that avalanches may fail even deeper now. Wind is peaking Tuesday night and there is a short break from precipitation on Wednesday.  This lull will help conditions settle for a quick period.

    The snow that fell in the last 2 days was heavier than snow that fell at the beginning of the weekend. This causes an “upside down” snowpack, where the heavier snow is sitting over a lighter layer. These conditions are oftentimes alarming, as avalanches usually fail easily on the light snow, with the denser snow acting as a slab on top. Stay alert for this as you travel by noticing thicker surface snow which then punches down to the lighter underlying layer. This upside down snowpack is present and reactive throughout the zone, but it is most concerning on leeward slopes at upper elevations where wind may have deposited snow into thicker slabs. Avoid slopes steeper than 35 degrees at this time, especially ones with signs of wind loading, and consider traveling around the runouts of large steep slopes as well.

    (2/13/2021) This widely propagating storm slab occurred Saturday.

  • Deep Persistent Slabs

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

    The deep persistent layer from mid January’s long period of high pressure is continuously getting buried deeper, making it more difficult to trigger. Observers are also noting it strengthening. No known avalanches occurred on this layer in at least a week. Despite this information, don’t forget about it yet. An avalanche failing on this layer is unlikely, but even the smallest possibility is alarming. Uncertainty remains, and it presents a very serious low likelihood/high consequence scenario. If you are in an avalanche which failed on this deep slab you probably would not survive.  

    Large triggers like cornice fall or motorized users have the best chance at affecting such a deeply buried weak layer. Continue to build in a wide margin for error and approach steep open slopes above 4500ft with a cautious mindset. Utilize good travel practices like riding one at a time and keeping eyes on your partners. If you must travel near or below steep upper elevation slopes, your best options are areas where avalanches on this layer already occurred.

    (2/11/2021) Natural slab avalanches along the east side of 3 Fingers area. These occurred after the most recent snowfall, in early February. They probably failed on the deep persistent weak layer.

Avalanche Discussion

We will probably see the sun Wednesday, so pay attention if the snow surface moistens on sunny slopes. Retreat to shady terrain when you notice the surface getting wet, before avalanches begin coming down. These are most likely to occur in steep areas with rock bands as an initiation point for avalanches. 

The neighboring Steven’s Pass zone is claiming the highest snow totals in the last 24 hours. WSDOT forecasters triggered multiple large and a couple of very large avalanches during avalanche mitigation along Highway 2 on Tuesday. An observer reported many natural avalanches on steep southerly aspects in the Steven’s Pass backcountry at about 5200ft on Monday. That zone received more snow than us, yet our conditions are not too unlike those at Steven’s Pass.  

Non-avalanche hazards also exist at this time including tree well and deep snow immersion. Find out more information about deep snow safety HERE.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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