Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

You'll likely encounter shallow wind slabs on a variety of aspects as east winds redistribute recent snow.  The combination of sun and slightly warmer temperatures raise the risk of cornice fall or a wet loose avalanche that could trigger a deeper avalanche in isolated areas.  Pay attention to overhead hazard and consider avoiding complex terrain at upper elevations. 

Avalanche problems

  • Wind Slabs

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

    Winds will shift to the E-SE on Wednesday night potentially forming new wind slabs on westerly aspects.  You'll want to use caution on any aspect you find recently drifted snow and can trigger a shallow wind slab, most likely below ridgelines, near convex rollovers, and in the tops of chutes.  These wind slabs may trigger easily but should remain fairly small and easy to avoid. 

    The more unlikely but consequential version of this problem will be isolated deeper wind slabs that may have formed a few days ago.  Deeper slabs are more likely to be found in higher elevation and cliffy terrain. The best way to handle this problem is to stay off and out from under rocky complex slopes, especially where you see larger cornices. Snow shedding from above or other avalanches could release these slides naturally. 

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    A few inches of new snow from Wednesday will be primed to come down on steep sunny slopes. An easterly breeze may make this problem vary across the zone.  If you start to see pinwheeling, rollerballs or natural wet loose avalanches, it's time to change aspects or move to lower angle terrain.  While you don't want to go for a ride even in a small wet loose avalanche, also make sure to look up and take stock of the overhead hazard.  Don’t linger on or under steep sunny slopes.  With a crust just under the surface, some of these slides could travel quickly downhill.

    (3/14/2023)

    Natural loose wet avalanche near Crystal Mt on the first sunny day following a storm. 

    Photo: Andy Harrington

Avalanche Discussion

2-6" of snow fell across the zone Tuesday night and Wednesday along with moderate to strong westerly winds. Shallow wind slabs were reported in the Crystal Mt backcountry on Wednesday. 

At this time of year the snowpack quickly becomes aspect dependent. Sunshine on Tuesday caused plenty of rollerballs and small loose wet slides. It also formed a new crust on the surface.  In more shaded terrain, cold snow lingered despite the sunshine and mild temperatures. The recent storm (Mon-Tues) brought 10-15 inches to most of the zone (with more at Mt St Helens). This snow seems to be bonding well with the old (3/12) interface. 

There have been a few notable avalanche observations this week. On Tuesday, we had two reports of the same avalanche in the Cowlitz Chimney’s area of Mt Rainier NP (NE, 6300ft). This very large slide likely failed during the recent warm storm. Two other very large avalanches occur on Mt St Helens early on Monday during the peak of the storm. The larger (D4) ran from near the crater rim to very low in the terrain (E, ~8000ft). We don’t know if these slides failed on older deep crusts or in just extremely wind-loaded locations. Either way, take note if you’re heading into remote alpine areas.

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