Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Increasingly strong winds ahead of a storm aimed directly at the West South should have no problem transporting light snow to form Wind Slabs on Sunday. Once the winds start to ramp up and you see actively blowing snow, consider stepping back your terrain choices. Unusual loading patterns may exist so don’t be complacent with your common travel routes. 

Avalanche problems

  • Wind Slabs

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

    The simplest way to look for wind-loaded terrain on Sunday will be to take note of actively blowing snow and where that snow ends up. Wind Slabs will be more likely as winds increase and often like to form on the leeward sides of ridgelines or near rocky features such as the base of cliffs or confined chutes. Be aware of the potential for unusual loading patterns due to the forecasted east wind event. Mid-slope loading and cross-loading are often more prevalent during these events and you may find Wind Slabs on slopes where you do not frequently see them. Shooting cracks or firm, hollow-sounding snow are good indicators that you are traveling in wind-loaded terrain and you should choose another route. If you can find a wind-loaded test slope, jump around on it to see how the snow reacts to your weight. If you identify actively loading slopes or find that blocks of snow are easily failing during your tests, seek out wind-sheltered terrain.

    Multiple professionals have reported that fresh and sensitive cornices have formed throughout the zone. The forecasted winds may help these hanging blocks of snow grow larger or fail naturally, so approach ridgelines with caution.

    (1/1/2022)

    This Wind Slab was intentionally triggered on a convex slope by NPS Rangers at Mt. Rainier National Park on New Year's Day. Take note of the textured snow surfaces as a visual clue that the wind has affected this area.

    Photo: NPS Rangers

Avalanche Discussion

Sunday morning should be the last bit of fair weather before increasing winds ahead of a potent winter storm impact the zone in the afternoon. Minimal new snow should fall during the daylight hours before heavy precipitation impacts the West South Sunday night into Monday. Recent observations indicate that a generally right side up snowpack exists above the Solstice Crust. Continue to be mindful of loose snow avalanches on steep features over 35 degrees if you are in wind-sheltered terrain.

We suspect most avalanche activity to occur above the 12/29 interface, but can’t rule out a step down to the Solstice Crust in isolated areas. Reports of very large avalanches have slowly trickled in over the past week from around the region and many of these avalanches are suspected to have failed down to the Solstice Crust. The most recent example was at Mt. Baker on 12/31 where a D3 avalanche left behind a ~550 foot wide, 2-5 foot deep crown. Although we haven’t confirmed one of these avalanches in our zone, that doesn’t mean that it can't happen. These avalanches appear to be erratic and unpredictable, but most appear to have occurred in wind-prone alpine terrain around the depth of the Solstice Crust. Take this information with you if you plan to travel to similar terrain on Sunday.

Regions covered