Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

A large storm dumped about a foot of heavy snow Friday night, and it's possible that you could trigger a slab avalanche failing near the bottom of the new snow layer. You're most likely to trigger an avalanche in a wind-loaded location, like below ridgelines or around features, and on steep unsupported slopes. Steer around steep, wind loaded slopes, or any other steep slopes if you notice red flags like long, shooting cracks. 

Avalanche problems

  • Wind Slabs

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

    You could trigger an avalanche in steep, wind-loaded locations on Sunday. A thick, heavy slab sits over softer snow in most areas. This slab structure was found to be stubborn on Saturday, however in wind-loaded locations the slab may be more reactive. Failures could occur at the bottom of the new snow layer, which started as a thick layer of graupel Friday evening, although this layer usually strengthens quickly. Another layer of concern which was found in pit tests Saturday was about 10cm  (4 inches) below the new snow, where a weak layer of facets formed during last weekend's cold snap. Avalanches could fail about a foot deep, or they could fail deeper depending on how much wind loading occurred.

    You can dig down to these potential weak layers to see if they exist and determine whether they are reactive in a relatively shallow pit.  Long, shooting cracks traveling out from your feet or sled, whumphs, and recent avalanches are some of your best indicators to stick to lower-angle terrain. Light snow is expected to fall Saturday night and scattered snowfall may occur through Sunday. Wind-textured or firmer surfaces hinting to wind slabs may be hidden by shallow deposits of less wind-affected snow. In addition to disguising old drifts, avalanches could occur in the shallower more recent snow layer as well.  Conditions vary throughout the zone and it's important to make your own decisions based on the clues you have. Avoid wind-loaded slopes greater than 35 degrees for Sunday. 

     

    A human triggered winds slab on a convex rollover near ridgecrest, a likely spot to trigger an avalanche on Sunday. 

    Photo: Eddie R

Avalanche Discussion

We received two excellent videos describing the snowpack setup in the new storm layers in the Baker backcountry,  and also saw a compression test. Check the videos out in the media section below. What we saw in the videos was similar to what we heard from a number of backcountry users on Saturday.  Results in pit tests pointed towards an unstable snowpack,  but the firm, heavy slab on top when on a slope-wide scale appeared to make it more difficult to trigger avalanches on the weaker underlying layers. There didn't appear to be an abundance of natural and human-triggered avalanches on Saturday. Due to the warm temperatures, the new layer appeared to be gaining strength throughout the day and slabs became less reactive. This doesn't mean triggering an avalanche on the layers at the bottom of the new snow is out of the question, and it's important to keep these concerns on your mind as you head out Sunday. Speaking of what you'll find on Sunday, warmer temperatures Saturday afternoon caused an abundance of rollerballs and small wet loose slides on steep slopes at the snow surface, which are not expected to be as active on Sunday.  Lower elevations mainly received rain Friday night, and as you near treeline, you'll begin to find a thicker coating of new snow.

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