Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sat
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Out of date — this forecast expired 3 years ago.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

Recently formed slabs of wind-drifted snow will be the greatest avalanche hazard.  Steer around steep terrain holding denser snow. You are most likely to trigger a slab on unsupported slopes like those above or around cliffs, or on convex breakovers. Dropping temperatures, tree wells, and deep snow will be additional hazards to plan for on Friday. 

Avalanche problems

  • Wind Slabs

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

    We are coming to the end of an active weather pattern and transitioning to a period of much colder, more stable weather. The widespread wind slab formation observed on Thursday will end in most locations, so we will be left to deal with stubborn, day-old slabs. With an afternoon wind shift, locations east in the zone could see another round of slab formation on south and west aspects. 

    Use the standard clues like cornices and wind-scoured surfaces to identify the loading pattern around you. Hand shears and test slopes on small, wind-drifted features can give you a sense of slab reactivity. While they will be harder to trigger on Friday, you can still find a wind slab, especially on very steep unsupported slopes or around rock buttresses. Fresh slabs from northeast winds will likely be more reactive. You might even see a few natural avalanches as well.

    (1/11/2024)

    A small but deep wind slab avalanche in West North. It was unintentionally triggered on a southeast aspect at 5400'. (HS-ASu-R1-S).

    Photo: Elias

Avalanche Discussion

Heavy snowfall was reported this afternoon from both Stevens and Snoqualmie Passes, with Hwy 2 at Stevens closing for a period. If traveling in parts of West Central near either of these zones be ready to see deeper new snow and greater avalanche danger. The best bet would be to reference the avalanche forecast for these zones if you are nearby.

Widespread wind transport from strong westerly winds was observed on Thursday in West North. Multiple wind slab avalanches to D1.5 were triggered, generally on slopes with an easterly aspect. Observers were able to get shooting cracks pretty much at will in wind-drifted terrain, especially in the morning when slopes were actively loading up and slabs were at peak instability.

While recent wind slabs are the type of avalanche you are most likely to encounter, you could still trigger a slab avalanche in wind-sheltered terrain. A layer of facets overlying the 12/30 melt-freeze crust is now buried 3-5’ deep (or deeper!) in the NWAC forecast zones around West Central. Avalanche activity is decreasing, but control work this week at Mt. Baker, Stevens Pass, and Alpental still produced avalanches that probably ran at the 12/30 interface.

Calmer conditions heading into the weekend will open the door to the bigger, steeper, and unsupported terrain where you might find one. Use caution approaching big slopes in the coming days and get a handle on snowpack structure and recent avalanche activity before considering more complex terrain.

Regions covered