Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Avalanche danger will likely start at Moderate, but will probably elevate to Considerable above treeline as the day progresses and snow slowly builds while wind increases. At the start of the day thicker, older slabs may be more stubborn, but as winds pick up with more new snow blowing around, begin shifting your travel to more conservative lines. When you see actively drifting snow and notice signs of instability like shooting cracks or recent avalanches, plan on avoiding steep, wind-loaded slopes. 

Avalanche problems

  • Wind Slabs

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

    Thick, stubborn slabs were reported in some areas around the zone the last couple days, while other, more sheltered areas had lower density, and less stiff or slabby snow. The day may start like that, but expect an increase in danger as wind speeds pick up and redistribute low-density snow into fresh, more reactive slabs. This is especially the case as you gain elevation above treeline.

    New deposits may only be a few inches thick, at least to start with, but they could grow to be six inches or deeper by the end of the day. When you notice wind moving snow around and actively drifting it, it's time to take a step back and reevaluate. Steer around wind-loaded slopes greater than 35 degrees, and avoid traveling on steep slopes if you cause long, shooting cracks or see recent avalanches.  

    When you start noticing small reactive wind slabs, keep in mind they may quickly grow in size or could possibly be deeper in other locations and it's time to start traveling more conservatively. 

    Photo: Adam Ü

Avalanche Discussion

Starting Sunday afternoon, we're in for continuous snowfall through midweek, although the tap isn't going to turn on until Monday night when we see snow really starting to stack up quickly. Avalanche danger will rapidly increase as this storm turns on Monday night. 

Many backcountry users traveled on steeper terrain Sunday, with minimal avalanches reported. However, there were a few reports of whumphing experienced, like in THIS observation from Sunday. A weak, faceted layer was found by a crust buried not too far beneath the surface. This layer may be present in some areas, which will be something to keep an eye on as more snow (weight) loads our snowpack. Additional layers in the top few feet may have weak interfaces, although nothing aside from this and one another report of whumphing have been very alarming. They'll be on our minds as the storm hits, as some of these weak layers may fail with the new load. 

In the last few days snow surfaces warmed and moistened at about 4500ft and down. We expect a slight cooling of temperatures into Monday, with less wet loose activity and rollerballs. Keep in mind surfaces may be variable where moistening previously happened. Otherwise, many near and above treeline locations and ridgelines likely have firm, wind-affected surfaces, whereas other more sheltered areas may have lower density pockets of snow. 

 

 

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