Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

This week, several waves of stormy weather have resulted in dangerous avalanche conditions in the mountains. Unstable slabs should be larger at upper elevations, on the volcanoes, or in wind-loaded terrain. Avalanches will fail more easily during or shortly after periods of heavy precipitation or wind. 

Avalanche problems

  • Storm Slabs

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

    This next storm wave will be the largest of the week, increasing both slab size and avalanche potential on Thursday. Use small test slopes, uptrack tests, or quick hand pits to look for failure points within or at the base of this week's storm snow. Cracking, upside-down snow, or blocks failing easily in your tests indicate that a slab avalanche problem exists and you should avoid slopes over 35 degrees. The depth and reactivity of slabs may vary across the zone based on storm totals or even from slope to slope due to exposure to wind. Large drifts, fresh cornices, or stiffer feeling snow can indicate that the wind has created slabs which may be more unpredictable than nearby storm slabs.

     (3/11/2025) 

    One of several human, remote, and natural slab avalanches from the Cyrstal backcountry on Tuesday. Slabs will only be thicker and possibly more reactive as more snow and wind impact the zone.

    Photo: Peter Sundberg

Avalanche Discussion

A slow trickle of avalanche activity has been reported this week as a series of storms have rolled through the West South, increasing the amount of snow over our most recent atmospheric river (AR) crust. Natural and human-triggered slabs, along with loose slides, have been noted. Even a few remotely triggered slabs were observed near Crystal Mountain on Tuesday. Most avalanche activity has been small, but this next storm could be enough to start worrying about slides large enough to bury you. Moderate to strong winds and periods of heavy precipitation should impact the zone, particularly in the morning hours.

In some respects, conditions are straightforward out there. We're not worried about any snow below the easily identifiable AR crust. So you have a good snowpack marker to target that will put a cap on potential avalanche size. Of course, there's nuance to everything in life, and our upper snowpack is no exception. Variable depth and layering exists above the AR crust. In some locations, weak surface hoar is suspected at the 3/9 interface. Approach slopes cautiously and gather plenty of data before committing, this variability could result in surprising avalanches.

We're generally on a cooling trend which should limit wet avalanche activity. But if lower elevations remain moist or the sun pops out and destabilizes new snow in the afternoon, be on the lookout for wet activity such as rollerballs, pinwheels, and small fan-shaped avalanches.

Regions covered