Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

A return to more active weather will bring rain, snow, and wind to the zone, resulting in increased avalanche hazard on Thursday. Take note of changing conditions throughout the day and look for wet avalanches anywhere rain is falling on dry snow. At upper elevations, some areas of the zone may see enough snow and wind to create Wind Slabs for you to steer around. 

Avalanche problems

  • Loose Wet

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

    On Thursday, look for the possibility of Wet Loose avalanches anywhere rain is falling on dry snow. This will be more likely on slopes that haven’t seen direct sunshine lately, particularly as you ascend in elevation. With snow levels expected to be around 5000 feet, it may be difficult to find slopes that fit the sweet spot where enough cold dry snow exists at an elevation that sees rain. If you find yourself in a location that fits this description, look for natural activity to begin at the onset of rain falling on dry snow. You may notice fresh fan-shaped avalanche debris or rollerballing. Your best mitigation technique is to retreat toward lower angled slopes, keeping aware of slopes above you that could shed snow onto your travel route.

    (1/1/2021) An example of Wet Loose avalanches from earlier this season from Glacier Hill on the Paradise Rd. Mt Rainier National Park. W, 4100'. Photo: NPS Rangers

  • Wind Slabs

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

    As you travel above the rain/snow line, you could find some freshly built shallow Wind Slabs to steer around. On the volcanoes, higher new snow totals and stronger winds are expected, possibly resulting in thicker slabs. Look for Wind Slabs to develop on leeward slopes near ridgelines or near rocky features such as cliffs and gullies. In some locations, they could overlay some weak snow grains and result in shallow but surprising avalanches. If you notice actively blowing snow or textured snow surfaces, look for wind-loaded terrain features to steer around.

    (3/7/2021) This small wind slab was intentionally triggered on a test slope near treeline. Small features like this can help highlight conditions on larger slopes. NW, 6100'. SS-ASc-D1-R2-S

Avalanche Discussion

The West South has had a largely aspect-dependent snowpack the past few days as sunny days and cool nights have created melt-freeze cycles on slopes that see direct sunshine. This has created firm surfaces in the mornings which have softened throughout the day, resulting in small Wet Loose avalanches or rollerballing activity. Without as much sunshine on Thursday, a stout melt-freeze crust should be in place on these slopes, minimizing Wet Loose potential. On slopes that haven’t seen direct sunshine, the snowpack has been more cold and dry, with wind-pressed surfaces or unconsolidated snow depending on your location. As more active weather starts to impact our zone, be sure to check the bonding of new snow to these various snow surfaces by using test slopes or hand pits before stepping into consequential terrain. Continue to take note of any cornices above you and give them a wide berth, especially during periods of rain. Although it may seem like we have made the transition to a springtime snowpack and winter is behind us, we are not there yet. Plenty of cold dry snow and layers of concern still exist in the mid to upper snowpack and this upcoming weekend should be more winter-like than spring-like. 

Regions covered