Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Start to think about slab avalanches anywhere you find over 6 inches of new snow. They’ll be easier to trigger on convex features or in wind-loaded pockets over 35 degrees. Your most significant concern at lower elevations will continue to be travel hazards.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    As snow piles up Wednesday night and Thursday, you could encounter small storm slabs at mid and upper elevations. The higher you ascend, the larger they should be. Use small test slopes and uptrack tests to determine how the new snow is reacting to your weight. If you find heavy snow over weaker snow, see shooting cracks, or blocks of snow failing in your tests, default to lower-angled terrain.

    Slabs should be thicker and possibly more reactive in wind-exposed areas than in sheltered terrain. In isolated locations, slabs could break in surprising ways - running on the 12/30 crust or stepping down to deeper layers. See below for more details.

    (12/8/2023)

    Hand pits are a great way to look at the recent storm snow. Look for strong over weak layers and places it fails easily. 

    Photo: Andy Harrington

Avalanche Discussion

A pattern change is bringing snowfall back to the mountains and increasing avalanche potential over the next few days. This started on Wednesday when roughly 2-3 inches of new snowfall was recorded at automated weather stations. Zones to the north reported that the snow was heavy and moist, with a poor bond to the old surface. Further south, the snow was drier and had a fair to poor bond to the underlying crust. Avalanche professionals at Snoqualmie Pass received easy failures on this layer on Wednesday using tilt and compression tests. As snowfall continues Wednesday evening into Thursday, you'll have multiple interfaces to investigate to determine how the storm snow is setting in wherever you're recreating. A convergence zone may clip the southern half of the West Central, while the northern reaches may get enhanced snowfall if the wind is stronger than forecasted. 

No new avalanches were reported in the West Central zone on Wednesday. Alpental Pro Patrol reported shallow wind slabs in the Snoqualmie Pass zone, while Baker Pro Patrol reported the snow being wet but no avalanches. All eyes continue to be on the storm Friday night into Saturday. The neighboring Stevens, East Central, and Snoqualmie Pass zones all have potential weak layers in the upper snowpack that are of concern heading into this storm cycle. The same concern does not exist in the West North due to multiple rounds of soaking rain.

 

Regions covered