Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 6 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Another warm and sunny day could result in wet loose slides or cornice collapses. Any triggered avalanche could potentially activate our buried weak layers, resulting in large, dangerous slabs. Make travel plans that give you options to avoid large open slopes over 30 degrees.

Avalanche problems

  • Persistent Slabs

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

    This is the avalanche problem that should be shaping your travel plans on Monday. While the likelihood of triggering these layers is up for debate, there is no disagreement among anyone who has taken the time to look - they are there, and they are spooky. This could result in dangerously large avalanches that break widely or even trigger remotely (from a distance).

    Due to last week's wind event, slabs could be thicker and potentially more sensitive in wind-loaded areas. As we add warmth to the snowpack, we introduce more uncertainty to an already unsettling problem. 

    This problem is difficult to diagnose in the field, so you likely won't receive much feedback before an avalanche occurs. Maybe you'll get a whumpfing collapse or a shooting crack, but that's not a guarantee. The best mitigation tool you have is terrain avoidance. 

    (3/1/2026)

    A snow machine triggered persistent slab avalanche in the neighboring East South zone on 2/28. This was fairly close to White Pass and a similar snowpack structure was found at the site. [HS- AMu-R2-D2-O @ NE, 6700']

    Photo: Joe Dellaporta

  • Loose Wet

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

    Monday will be the warmest day of this mini heat wave, meaning wet avalanches will again be on the docket. 

    There will likely be a surface crust first thing in the morning. But once it breaks down and the surface gets warm and sticky or you see snow shedding on steep slopes, you'll know that wet avalanche activity could soon follow. That will be your cue to head for shaded, low-angle terrain, staying aware of slopes above you.

    This avalanche problem is typically easy to manage, but with persistent weak layers lurking below the surface, it becomes more complex. In addition to fanning out and growing in size as they descend, the threat now exists that they will trigger larger and more dangerous persistent slab avalanches. 

    The same logic applies to cornice failures. A danger in their own right, they could be the trigger that collapses our weak layers during this heat wave.

    (3/1/2026)

    A wet loose slide that then pulled out a small slab as it descended. Wet loose or cornice failures could trigger slabs on the slopes below due to a weak upper snowpack.

Avalanche Discussion

We're in the midst of a heat wave in the West South zone. Uncertainty around our persistent weak layers will rise right along with the temperature on Monday as we look forward to the warmest day of the week. 

So what does that mean for the 2/13 and 2/7 with their buried surface hoar and facets? Well, in other parts of the region, we have seen an uptick in activity on these layers this weekend. On Sunday, a small loose avalanche pulled out a small slab as it descended in closed terrain at Crystal Mountain. It wasn't a persistent slab, but it illustrates the point. On Saturday, a snowmobiler triggered a persistent slab in the neighboring East South zone and was partially buried.

A weak snowpack is well-documented in our zone, and we've seen a lot of activity on these layers over the past week. If we add stress, whether from a loose slide, cornice collapse, or just solar input, these layers could roar back to life. The dynamics behind this sort of behavior are not well understood in the avalanche world, but if you've been around long enough, you've seen it happen.

So while we don't have much direct feedback on these layers from this past weekend in our zone, that doesn't mean this problem is over and done with. The likelihood of triggering may be trending down, but take some time to discuss the conditions and your acceptable level of risk with your partners. This snowpack is atypical for the Cascades, and your normal assessments and travel plans may not hold up. You can't do anything about the weak layers in the snowpack, but you can choose terrain that matches your risk tolerance and skill set.

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