Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Thu
Alpine
2 · Moderate
Treeline
1 · Low
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Out of date — this forecast expired 3 years ago.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

Upper elevations could be harboring small pockets of wind-drifted snow for you to avoid on Wednesday. They could be sensitive and run on a slick underlying crust. Travel conditions are still challenging in the mountains, but at least it should be a warm and sunny December day. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    At upper elevations above the rain/snow line, you could encounter shallow wind slabs that formed on Tuesday. We expect these to heal fairly quickly in the relatively warm weather and sunshine but are worth avoiding for another day. They will likely be on leeward slopes near ridgelines or rocky features such as cliffs and confined chutes. You can look for features that are “fatter” compared to the surrounding terrain or look pillow-like. You may also notice some textured surfaces nearby or cracking of the surface on wind-loaded slopes.

    (12/19/2023)

    This sharp lip formed on a ridgeline during Tuesday's storm due to blowing snow. Look for potential wind slabs on the leeward slope below it.

    Photo: Morgan McGonagle

Avalanche Discussion

Tuesday’s storm wasn’t a big snow producer for the West South, but areas near the crest squeezed out 4-5 inches at upper elevations before freezing levels started to rise. Crystal Mountain Pro Patrol reported shallow but sensitive slabs breaking at the newly formed 12/19 interface during their morning mitigation efforts. Although the snow was moist, the wind was strong enough to actively move it onto leeward ridgelines. In more sheltered locations, rollerballs were reported in the moist snow, but no wet avalanches were observed.

Information from other areas of the zone is limited. Weather station data relays that similar conditions to Crystal likely existed at White Pass, while Paradise received all rain at the parking lot. Snowy conditions similar to those at the crest are likely as you ascend in elevation on the volcanoes.

On Wednesday, freezing levels are expected to elevate in combination with sunshine. However, it's the winter solstice this week, so the sun’s influence should be minimal. Even so, you might see some rollerballs on steep slopes or snow shedding from trees and rocks. If that’s the case and you are sinking in moist snow past your ankle, be suspicious of small, loose avalanches on steep, sun-exposed slopes. 

Gushing creeks, exposed boulders and logs, holes, and variable surfaces have provided challenging travel conditions over the past week for backcountry travelers. Expect this to continue until we get more significant snowfall. Maybe this weekend…?

Regions covered