Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

A potent winter storm is about to pummel the West South and dramatically change our snowpack. High precipitation rates and strong winds will help an uncharacteristic Pacific Northwest snowpack to produce widespread avalanche activity. Best to let this storm run its course before going anywhere near avalanche terrain.

Avalanche problems

  • Storm Slabs

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

    This storm should produce more dense snow than we have experienced lately, creating an upside-down snowpack primed for slab avalanches. We expect most slabs to be reactive at the new/old snow interface or on recently buried layers in the upper snowpack. Slabs will be thicker and possibly more sensitive in wind-loaded terrain and there is plenty of loose snow available for entrainment to help any slide grow large. These avalanches will be more likely to fail naturally during periods of high precipitation or winds. At any point, shooting cracks or whumpfing collapses are signs that the snow is unstable and that you should head for slopes under 30 degrees. 

    In adjacent zones, recent observations indicate that this problem may extend into areas commonly referred to as “safe” on high hazard days such as treed areas and that these avalanches could break in surprising ways by propagating widely or connecting terrain features. This may also be the case in the West South, but the overall stormy conditions should be enough to steer you away from avalanche terrain for the day.

    (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

The West South is right in the bullseye for this storm’s track. Although we have seen storms with bigger snow totals in the past, the unique snowpack setup in the West South combined with the ferocity of this storm is enough to tip the scales and drive very dangerous avalanche conditions. Observations from Sunday indicate that the transition to an unstable snowpack had already begun with a couple of reported natural and human-triggered avalanches in wind-loaded terrain. Don’t treat this storm like a normal loading event or PNW storm, it is not. Weak snow surfaces, rapid loading, high to extreme winds, and a slight warming trend all point to widespread avalanche activity. Even if much of the natural cycle occurs overnight Sunday into Monday during the onset of the storm, instability should linger into the daylight hours and continue producing avalanches.

Regions covered