Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

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

A late March storm is ready to hit the West South zone on Wednesday, resulting in dangerous avalanche conditions. It's warmer and wetter this time of year, so you'll need to manage both wet and dry snow problems. When in doubt, default to slopes less than 35 degrees where you're less likely to trigger a slide.

Avalanche problems

  • Storm Slabs

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

    On Wednesday, incoming snow and fluctuating freezing levels should result in dry snow problems at middle to upper elevations. Use quick hand pits to check for heavy snow over weak snow or a poor bond to the underlying surface. Uptrack tests and small test slopes can help indicate how the new snow reacts to your weight as a traveler. It's springtime, so the moisture content will likely vary between wet and dry, depending on your elevation or even the time of day. Regardless, slabs will be easier to trigger in wind-loaded areas or on slopes over 35 degrees. When in doubt, seek out lower-angled terrain.

    (3/10/2024)

    Example: A skier-triggered slab mid-slope on a northerly aspect. Similar avalanches could occur at mid to upper elevations on Wednesday.

    Photo: Andy Harrington

  • Loose Wet

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

    It's a springtime storm, so yes, you'll need to manage wet problems as well. The driver for wet avalanches could vary throughout the day - heavy new snow, rain on recently fallen dry snow, sun breaks, or afternoon warming. You can track how the snow surface changes throughout the day in response to the weather to determine which factor is at play. Or you can keep it simple - anywhere you encounter moist snow deeper than your ankle, you should think about wet avalanches. These slides often start small but can grow large as they descend and fan out. They'll likely be heavy and can be deceivingly powerful. Don't get tripped up by one near a terrain trap where the consequences could be amplified. 

    (3/18/2024)

    A skier-triggered wet loose avalanche that entrained snow as it gouged into older layers. 

    Photo: Crystal Mountain Pro Patrol

Avalanche Discussion

Wednesday's weather should have all the components of a winter storm to start - moderate precipitation, strong winds, and low freezing levels. However, springtime warming will help the freezing level rise throughout the day. We're expecting rain and mixed precipitation at lower and mid-elevations. The most dangerous avalanche conditions could exist near the fluctuating rain/snow line or on the southern volcanoes where higher storm totals are anticipated. 

Snow will fall primarily on moist surfaces. Modest snowfall on Tuesday helped to build depth over a crust formed from last week's warm weather. White Pass Pro Patrol reported the new snow warmed throughout the day, resulting in rollerballs and small debris piles. At upper elevations, small wind drifts failed easily due to intentional ski cuts.

Deeper in the snowpack, you can still find facets on and near the Early February Crust, but these layers have significantly gained strength. Additionally, they are becoming bridged by the crust mentioned above. It would likely take a very large trigger in rocky, shaded terrain to produce a slide. 

The lower elevation snowpack took a massive hit during the recent warm weather. Expect shallow coverage, open creeks, and lots of tree debris. Not much, if any, new snow accumulated below 4500 feet around the zone. We'll likely end up in the same boat on the tail end of this event, but as temperatures fluctuate throughout the day, small wet activity can't be ruled out at the upper end of the lower-elevation band. 

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