Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

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

Large and destructive natural slab avalanches are expected to fail naturally and with a human trigger on Monday. Avalanche activity will likely elevate as the storm deposits more snow throughout the day both at upper elevation and down lower, where wet loose avalanches could run as well. Avoid traveling on steep slopes, and steer around lower-angle terrain beneath large steep slopes near and above treeline. 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–2.5

    Believe it or not, this storm is not favoring the West North zone. That being said, the amount of water we're receiving is not something to be laughed at. Large, natural avalanches are likely and human-triggered avalanches are very likely near and above treeline. This is especially the case as more snow builds up and the wind peaks later in the day. In general, during periods of higher snowfall intensity or wind, you can expect more avalanche activity.

    Forecasts are showing storm totals running at a little over 1.5 inches of water, or about a foot and a half of snow, by the end of the day. A wavering, "warmer" freezing level of 3500ft also means that our snowpack could be set up with heavier snow on top of lighter snow, or an "upside down" snowpack, which tends to create more storm slab avalanche activity. At mid to upper elevations, and especially as the day progresses and more snow builds, steer around not only steep slopes but lower-angle terrain beneath large steep slopes as well. 

    Large, destructive slab avalanches like this one could fail naturally or with a human trigger on Monday. 

    Photo: Adam Ü

  • Loose Wet

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

    You'll encounter wet snow at lower elevations on Monday. Moist or wet snow, especially newer layers near the surface, could run on steep slopes during the day. You may just see rollerballs, or enough snow may lose cohesion that wet loose avalanches could run in the new snow layer.

    These avalanches would likely be on the smaller side, but depending on how much moisture is present in the new snow layers, they could grow large. Wet loose avalanches could initiate and then release a slab once enough mass builds up.  At lower elevations, avoid steep slopes and if you see rollerballs or any additional avalanche activity, steer around the runouts beneath avalanche paths as well. 

    An old photo of rollerballs and small wet loose avalanches in Herman Gulch, similar to what you might see on Monday. You could probably encounter larger ones on Monday, too. 

    Photo: Lee Lazzara

Avalanche Discussion

There is a very small chance that with the added weight from the storm, an avalanche could step down to a very subtle weak layer, which may be 4-6ft below the snow's surface. The last time an avalanche occurred on this layer was over a week ago, on Feb 11. We're keeping this concern on our radar through this storm as the final test on the layer. If an avalanche does occur, it will be very large and destructive, and could travel down, below treeline. 

As is oftentimes the case, weather and precipitation amounts will likely vary throughout the zone, so evaluate conditions and adjust the forecast as needed for your travels. 

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