Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Very dangerous avalanche conditions should develop Friday night and into Saturday morning for parts of the West South zone. Natural wet avalanches of various types and sizes could occur. Give avalanche terrain a wide berth, including where slides run and stop.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    You’ll certainly see plenty of wet loose avalanches as rain reaches high into the mountains on Saturday. However, it’s the much bigger and deeper slides we’re scared of. Very large wet slabs, cornice falls, glides, and wet loose slides that gouge into older snow layers could all occur as water moves deeper into the snowpack. 

    Most of this avalanche activity is expected at middle and upper elevations where a more layered snowpack persists despite the recent mild weather. However, bigger slides could descend into the lower elevation band from very large avalanche paths in a few isolated areas. 

    Give the mountains time and space to deal with this warmup. Avoid areas where avalanches can start, run, and stop particularly in the higher terrain.

    (1/19/2024)

    Example: A large natural wet slab avalanche on Panorama Face, Paradise Mt Rainier. This crown stretches nearly the entire width of the feature. SW, 6600ft

    Photo: Northwest Avalanche Center

Avalanche Discussion

This is a very tricky forecast. An atmospheric river will bring rain to near the top of our forecast area (8000ft). “How much rain?” is a much more challenging question. This could cause the avalanche danger to peak in different parts of the zone at different times. It also means we could peel back layers of the snowpack in successive wet slab cycles. Add to that the tendency for wet slabs to continue to fail after the intense precipitation and you have the makings of a multi-day avalanche event. 

Ultimately, wet slabs are a very uncertain problem. Timing, size, likelihood… they’re all in question. We are confident the setup is there; we just don't know if the precipitation amounts will be enough to tip the scales. Two main snowpack conditions seem common in the zone. 

Volcanoes: This snowpack has gone through more of a transition over the past few weeks. However, multiple interstorm layers and sections of weak wet snow linger. While overall, the snowpack is stronger, these areas (Rainier and Mt St Helens) will receive the bulk of the precipitation. 

Crest Areas: The snowpack in places like Crystal and White Pass is still very cold, dry, and layered. Only the top few inches became wet during the past week. Below, you can see every weak layer going back to the Solstice Crusts in mid-December. While these areas will see less rain, the snowpack is much weaker. 

On Friday, NWAC forecasters took one last look at the snowpacks at Mt Rainier and White Pass. We feel confident in the structure. Now, we’ll have to see how it plays out.

Regions covered