Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Fluffy snow is hiding buried weak layers capable of producing a dangerous and consequential avalanche. Avoid this hazard by keeping off steep open slopes facing west, north and east. Safer avalanche conditions and incredible snow quality can be found on lower angle slopes, in the forest, and on south-facing terrain.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    1 ½ to 3 ½ feet of snow sits atop the January Drought Layer (JDL) and the 1/10 complex, and both harbor weak faceted snow and crusts. It has been close to a week since the last reported avalanche occurred on one of these layers, however, whumpfs and poor test scores continue to point to an untrustworthy snowpack waiting for a backcountry traveler to find the “sweet spot” and trigger an avalanche. The likelihood may be decreasing, but that’s of little comfort if you happen to be the one that goes for the ride.

    Because of the spatial variability with this problem, it’s not possible to determine with certainty which slope is okay and which may slide. The only surefire way to manage the hazard is through a disciplined tour plan that avoids steep and open shaded slopes.  

    If you decide to roll the dice, stack the odds in your favor. Choose planar and supported terrain with clean runouts, no terrain traps, only expose one person at a time, and minimize your exposure on the ascent. Areas where the slab is thinner, such as around rocks, trees, and locally wind-scoured spots may act as trigger points. Be especially wary of these specific features within wind-loaded start zones. Complex terrain often holds this dangerous combination of thicker and stiffer slabs with locally thin areas on the slope.

    (2/3/2025)

    A skier triggered persistent slab avalanche near White Pass. This slide released over a 100ft wide and 2-3ft deep. WNW, 5600ft SS-ASu-D2-R2-O

Avalanche Discussion

A loud whumpf is the only new (and discomforting) piece of information from the West South. With quiet and cold weather, we don’t expect anything much to have changed. We still don’t trust this snowpack and probably won’t for a while yet.

On Tuesday, a few other things could impact your day. Expect very cold temperatures, especially when you factor in the wind chill. Plan accordingly and appreciate what that could mean in the event of an accident. Increasing overnight winds could form shallow wind slabs before daybreak. Identify and steer around freshly wind-loaded slopes by looking for textured snow surfaces and lens-like deposits. In addition, fresh snow will likely see sunshine for the first time and a loose avalanche or two could come down. They shouldn’t be particularly impactful unless they knock you off your feet in a critical location.  Remember, you could find different, potentially more reactive, persistent slab conditions if you push further into the mountains.

A final thought related to the persistent slab and snowpack tests. Where the ECT asks “Can I break it, and if I do, will it propagate”, the PST asks, “When I break it, will it propagate”? As the slab gets thicker and stiffer, the latter may be a more appropriate question, as one can always find the thin spot. Lastly, an unstable test result should be a red light, but a stable result should never be used as a green light. Test for structure and instability, not stability.

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