Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Fresh snow, strong winds, known weak layers, and recent avalanches all point toward potentially dangerous avalanche conditions. You’re most likely to trigger a slide in wind loaded areas, at higher elevations, or in more complex rocky terrain.

Avalanche problems

  • Wind Slabs

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

    Strong winds from various directions likely build fresh slabs in some odd places and on a variety of aspects. By Thursday morning, the bulk off the active wind loading should be over. You’ll need to look for clues that help discern where local winds formed potential slabs. Textured surfaces, wind lips, and sharp drifts all point towards possible wind slabs. 

    Watch out for pillow-like drifts along exposed ridges, in the tops of chutes, near the base of cliffs, and down the sides of gullies. In some cases, these slab could sit over a firm crust and trigger easily.

    .

    (2/18/2025)

    This natural slab avalanche was spotted Tuesday near White Pass ski area. NE, 6600ft. 

    Photo: White Pass Ski Patrol

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    There are several older snow layers that may produce avalanches. The most recent (2/13), seems to be the culprit in numerous slides on Wednesday near Crystal Mt. In general, these avalanches would be more common on shaded slopes. However, in some locations, avalanches have run on very soft snow just above the 2/13 crust on more southerly aspects. 

    Recent avalanches, weeks of snowpack tests, and well know weak layers are all classic ‘bullseye” data. Don’t expect these layers to talk to you or crack. The only way to really look at it will be to dig. However, given the spatial variability of these layers, even snowpack tests can make it seem safer than it is. While the recent storms haven’t been big, they have added weight to these persistent weak layers likely making them a bit less predictable. Discuss the consequences of a slide before choosing to step into larger steep slopes.

    (2/15/2025) Photo: Joe Dellaporta

  • Loose Wet

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

    Significant sun breaks could lead to snow shedding from rocks and trees. These snowballs often result in natural loose avalanches. While most of these slides should be small, they might entrain all the new snow and run on a thin crust beneath allowing them to grow larger and travel further. 

    Pay attention to what’s above you and don’t linger under very steep slopes during periods of sunshine. If it’s cloudier than expected, you might not see any wet loose issues.

    (12/5/2024)

    Example: Wet avalanche activity off the Lower Wapowti Clever south of the Wilson Bench. 

    Photo: Dallas Glass

Avalanche Discussion

Thursday should provide a relative break in the action. Expect the new snow to be the most dangerous in the morning and during periods of warm sunshine. 

Persistent Weak Layers: Here’s a summary of the PWLs in the West South

  • 2/13: S aspects: often a sun crust with weak snow just above, N aspects: rimed snow grains and/or surface hoar
  • January Drought Layer (JDL): W-N-E aspects: small facets often with a thin crust. 
  • 1/10 Complex: a thicker layer of alternating larger facets and weak crusts. 

At lower elevations, you may find wet heavy snow or a new breakable crust. While you may see a few very small slides, the hazard should be confined to the upper portion of this band.

Regions covered