Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Even as the fire hose starts to ease on Sunday, natural wet avalanches could continue. These slides should be fewer in number, but their size and consequences are still quite scary. Pay attention to the slopes above you, and limit any time you spend in places avalanches could run or stop.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–3

    Observations from Saturday suggest that at least parts of the zone underwent a very large wet avalanche cycle. This could continue during periods of heavier rain Saturday night. As the rainfall tapers Sunday, natural slides won’t just stop on a dime. Water will continue to percolate through the snowpack, and some slopes could fail. You may see wet slabs, glides, cornice collapses, and wet loose slides that gouge into older snow. The bigger avalanches will likely occur when a blob of snow shedding off a rock or a much smaller slide triggers weakness deeper in the snowpack. 

    The likelihood of wet avalanches should slowly decline over the day. However, the unpredictability and massive consequences won’t change. Plan routes that help limit, or even totally eliminate the time you spend on or under steep slopes. 

    With the upper snowpack a wet sloppy mess, you may still trigger a slide on very steep slopes. These thick heavy wet loose slides could then step down and release one of the nasty beast discussed above.

    (1/27/2024)

    This large natural wet slab failed about 3ft deep on Saturday (1/27) afternoon. N, 6800ft, WS-N-D2..5-R2-O

     

    Photo: Crystal Mt Ski Patrol

Avalanche Discussion

Rainfall totals on Saturday afternoon exceeded 2-3in through most of the West South zone. Another 0.5-1.5 inches should fall Saturday night and into Sunday morning. Rain reached well above our forecast region (~8000ft). Despite the brutal weather, we heard about several big avalanches from various parts of the zone. The USGS detected a very large (D3+) avalanche on Mt St Helens (E, 8000ft) and 9 bigger (~D3) slides on Mt Rainier (various aspects) Saturday morning. Crystal Mt Ski Patrol also witnessed one large wet slab (D2.5) mid-afternoon during a relative lull in the storm (N, 6800ft). 

This storm cycle continues to have our attention, not just for the rainfall totals or the high snow levels, but also for the dry weak snowpack that was present prior to the rain event. For several weeks, we’ve been talking about persistent weak layers with the snowpack across the zone. A near-steady trickle of very large slides spoke to the lingering nature of these facets and crusts. While not identical, snowpacks near both the volcanoes and areas closer to the Crest (Crystal and White Pass) were cold, dry, and layered. You could see storm layers from January and much older crusts going as far back as the Solstice in mid-December. This rain-on-snow event is a very big change for these weaker snowpacks, and could result in a prolonged avalanche cycle.

Regions covered