Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

Very dangerous avalanche conditions with numerous large natural avalanches big enough to kill you are expected Thursday in the West South zone. This is not the day to try to outsmart the hazard. Stay well away from any slope where avalanches may start, run, or stop until this storm ends.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    In some ways this forecast is very simple: conditions will be very dangerous on Thursday. Very heavy precipitation, significantly warming temperatures, and strong winds will all combine to cause widespread natural avalanches all across the West South zone. Don’t try to tiptoe around this one. Stay out of all avalanche terrain including where slides can run and stop. Any avalanche could be large enough to bury and kill you. In some locations, slides may entrain significant snow, break into older layers, and grow very large and destructive. 

    Often we see lower danger at lower elevations. That will not be the case Thursday. With all the new snow, you may see large natural avalanches even well below treeline and in some unusual locations. Any open slope over 30 degrees should be suspect. Just because you haven’t seen it slide before doesn’t matter. Stay off of and out from under any steep open slope.

    (1/4/2022) Strom slabs like this are expected Thrusday, but will be much deeper and more deadly. [N-E 6300']

    Photo: Dallas Glass

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    Warming temperatures will eventually bring rain and heavy wet snow to near the top of the below treeline band. As it does so, we will see a change to wet avalanche problems. We expect large loose wet and wet slab avalanches. When you see the snow change to rain anticipate another round of natural avalanches to follow. This isn’t an avalanche problem you want to mess with, and the travel advice stays the same. Stay out of all avalanche terrain Thursday.

Avalanche Discussion

The West South is right in the middle of the bullseye for this powerful storm. Often we talk about timing or locations to hone in the forecast, but that’s not the case for this event. When we see forecasted precipitation amounts of several inches of water (multiple feet of snow) with warming temperatures for all locations we expect the very dangerous conditions to be widespread from Crystal Mt to Mt St Helens, from Paradise to White Pass, and everywhere in between. Due to the dynamic and ongoing nature of this storm, you could see several rounds of natural avalanche activity. The more snow that stacks up, the bigger each of these avalanches cycles could become. While we've seen several large storms in the West South, this will be the largest and most widespread avalanche cycle of the season to date.

Several natural cornice failures occurred on 1/4. As these waves of snow grow larger during the storm they may fail naturally and become large triggers hitting the slopes below.

If the storm and avalanche hazard weren’t enough, roof avalanches, tree bombs, deep snow suffocation, and treewells all round out the dangers you face if you head into the mountains. It maybe best to sit back and let this storm play out from somewhere other than the backcountry.

Regions covered