Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

Remain wary of triggering an avalanche in large terrain with steep rollovers and slopes wind loaded with snow as the storm snow continues to settle. We're coming out of an active storm cycle and there are a lot of uncertainties with the snowpack at this time.  Steer around steep, unsupported features, high-consequence terrain, and steep wind-loaded slopes on Monday. 

Avalanche problems

  • Storm Slabs

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

    Your main avalanche concerns are on steep, unsupported terrain where residual storm snow instabilities may be present, and on steep, wind-loaded slopes. Natural avalanches and reports of whumphing and easy failures during and just after the storm slowly shifted to harder test results and fewer signs of instabilities as the snow settled in neighboring zones. We are still concerned about higher consequence areas and larger slopes, especially as you make your way towards above treeline elevations, where it may take more time for the storm instabilities to settle out. 

    Steer clear of steep, unsupported terrain or steep rollovers on Monday. Pay attention to snow surfaces, noting whether the snow gets thicker, or heavier feeling, which might help you determine whether wind loading has occurred in that area. Search for ripples or wind sculpted snow, and obvious clues such as long shooting cracks. Avoid steep slopes where you encounter these conditions as well.

    An example of a large storm slab avalanche which ran on a convex feature, similar to an avalanche you might be able to trigger on Monday.

    Photo: Adam Ü

Avalanche Discussion

Sluffs, or small loose dry avalanches might happen naturally or with a human trigger in steep areas where low density snow exists. Skies will be mainly clear on Monday, and rollerballs and small wet loose avalanche may occur on southerly slopes, something to pay attention to as the day warms up. I traveled to 4400ft in the Highway 2 corridor near Skykomish on Sunday. I saw both very small dry sluffs earlier and a few small rollerballs coming down as temperatures reached freezing level mid-morning onwards. I dug several pits from southwest, through west to north, and found a few shallow storm snow instabilities. I also repeatedly saw hard compression test failures within a layer beneath the new storm snow, just over a foot down. I searched hard for surface hoar, as that's been on our radar lately, but was unable to find it. 

Several nearby zones have found buried surface hoar, which was buried about a foot deep before the additional foot of snow fell. In the West North zone we received THIS observation on Friday, where a small (D1) avalanche was triggered in an open meadow below treeline. They found feathery crystals, which were likely surface hoar, below the 40cm thick slab.  Although it's been found in a number of zones, very few avalanches have been reported as failing on it thus far. 

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