Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

Heavy precipitation, warming temperatures, and strong winds will create very dangerous avalanche conditions on Sunday, especially at mid and upper elevations. You may see large and destructive natural avalanches travel near the bottoms of their runouts. Avoid heading into or underneath avalanche terrain.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2

    We expect this stormy weather to overload the snowpack and cause large natural storm slab avalanches especially in areas that receive higher snow totals and during periods of heavy precipitation. These slides may break widely, entrain additional snow, and run far distances. Given the size and scope of this weather event, stay out of any location where an avalanche may start, run, and stop. While we aren’t forecasting high danger below treeline, avalanches originating at higher in the terrain may travel into lower elevations. Continue to limit your exposure to larger avalanche paths even down in the forest. 

    In areas receiving less snow, strong winds will still drive dangerous conditions and a significant wind slab problem. Slides may trigger easily and break widely. Just because you aren’t seeing the brunt of the storm doesn’t mean you’re safe. Stay off of slopes greater than 30 degrees in these locations.

    (2/20/2021) This human triggered wind slab avalanche occurred Saturday in the Crystal backcountry. S, 6000' Pickhandle Pt. Photo: Jen Daniels.

  • Loose Wet

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

    There’s a lot of snow on the ground, even at lower elevations. As the rain-line begins to march up the mountain, you will see avalanches. Expect plenty of natural loose wet slides from very steep slopes. In large avalanche paths, these avalanches may entrain substantial amounts of snow and grow larger. If you see rain on snow or experience a wet sticky surface, stay away from and out from under nearby steep terrain. 

    While it’s less likely, you may see a few natural wet slab avalanches occur. These would be most likely near the rain line as it reaches elevations above 4000’. Wet slab avalanches are very difficult to predict and better handled by avoidance. If you see new crowns, dial it back even at lower elevations and seek out slopes well away from avalanche terrain.

    (1/1/2021) Natural loose wet avalanche at Glacier Hill on the Paradise Rd. Mt Rainier National Park. W, 4100'. Photo: NPS Rangers

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3

    This weather event should significantly test the deeper weak layers in the snowpack in most locations. Even though it’s been quite a while since our last recorded avalanches on these layers in the West South, recent stormy weather severely limited observations. You could see naturally occurring deep slides, or shallower storm slabs may step down into these older layers. On Saturday an avalanche failed on the mid-Jan layer near Stevens Pass after more than a week without avalanches. Give this scary problem a wide berth. Avoid traveling through even the runouts of large avalanche paths until this storm cycle concludes.

    (2/20/2021) This deep avalanche likely failed on the mid-Jan crust Saturday near Stevens Pass. S, 4900' Photo: Wash DOT NCR.

Avalanche Discussion

Expect the avalanche danger to quickly begin to rise Saturday night and into Sunday as the storm really begins to ramp-up. While this event isn’t as warm as some of our previous atmospheric rivers, it is no less potent. It should result in several natural avalanche cycles that may peak at different times for different locations. 

If this significant weather event and the above avalanche problems aren’t enough, natural cornices failures, glide avalanches, and wind slabs are also on our minds. Given this long and complex list of overlapping potential avalanche problems, this isn’t the time to try to thread the needle. If you choose to head into the backcountry, select simple terrain where you can easily identify and avoid avalanche slopes to manage your risk. Give this storm and potential avalanche cycles time to play out. 

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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