Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

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

Large natural avalanches were reported as the storm bore down on us Friday night into Saturday. The snow came in a bit differently than many of our Cascades storms, so remain on your guard and avoid traveling out on steep slopes on Sunday, especially if they are wind loaded.  This is a little more spicy than your typical Cascade post-storm day, and it is likely that you could trigger a large, destructive avalanche that could kill you. 

Avalanche problems

  • Storm Slabs

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

    Your weight on a slope can trigger a large, unsurvivable avalanche on Sunday. Around 2 feet of snow fell in the last 48 hours, and it still needs time to adjust before you step out on steep slopes. The storm came in with cooler temperatures before ending warmer, and this made the snow "upside down", where heavier snow sits over lighter snow due to the temperature differences.  One observer reported "wallowing" in the snow on Saturday. Another observer noted whumphs in from flat areas, which are red flags that the snowpack is unstable. He remarked that early afternoon, his board went from sinking 20 inches into the snow to sinking 6 inches over the course of an hour as temperatures warmed.  This is a clear indicator that the snow was rapidly "slabbing up". Natural avalanches were reported, and one observer was able to get close to one after it had occurred, suspecting it failed on or within the new snow layer, but with some wind effect, noting a 3ft crown. 

    These weak snow indicators aren't going to go away overnight. Natural avalanches are expected to decrease in likelihood, although they remain possible. A human-triggered avalanche is still likely. Any steep slope where this new snow layer sits thickly upon it is suspect. In locations where wind drifted the snow even deeper you can expect it to be even easier for you to trigger an avalanche.  With these concerns, steer around slopes steeper than 30 degrees on Sunday. 

     

     

     

    Large cracks shooting out from your feet or snowmobile are indicators of a weak snowpack. Avoid steep slopes if you see this, but for today, stay off steep slopes before you get this clue. 

Avalanche Discussion

Sluffs, or small loose dry avalanches might happen naturally or with a human trigger in steep areas where low density snow exists. We may see some sun later in the day, and freezing levels will rise a little higher than the previous day.  We don't expect it to get warm enough for snow surfaces to moisten and small wet loose avalanches to occur, but keep it in mind as the day progresses. As the snowpack gets deeper, it's time to start thinking about tree wells and snow immersion suffocation (SIS). Remain alert to this very real hazard when traveling near trees, and check out the video below for more information about it. 

Before the storm on Friday, an observer reported triggering a small avalanche in an open meadow below treeline. You can read the observation HERE. The observer found feathery crystals, which were likely surface hoar, below the 40cm thick slab. This is the only piece of information we've got indicating that there may be a buried surface hoar layer, now buried closer to 3 feet deep.  You'd most likely find it in sheltered below treeline meadows. A number of zones reported finding this layer in the last few days, although very few avalanches have been reported as failing on it thus far. With additional load more avalanches could start occurring. 

 

Regions covered