Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Dangerous avalanche conditions will continue on the first day of spring as warm and sunny weather bakes our snowpack. Wet avalanches can occur without warning and could result in deeper, unsurvivable slides in isolated locations. Avoiding steep open slopes is the best way to manage the risk until temperatures cool and the surface freezes.

Avalanche problems

  • Loose Wet

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

    Continue to minimize your time in and below avalanche terrain as our heat wave continues on Tuesday. You'll likely encounter some form of wet avalanche if you're in the mountains. Whether that slide is loose, a cornice fall, glide,  or snow shedding from rocks is difficult to predict. Most avalanche activity should be loose and confined to the surface snow. However, a few of these may gouge down into older snow, growing large in the process. Of course, those shed-type slides could be the more dangerous and are almost impossible to predict.

     

    (3/18/2024)

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

    Photo: Crystal Mountain Pro Patrol

  • Deep Persistent Slabs

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

    Plenty of uncertainty surrounds the deeper persistent weak layers in the snowpack. Facets on or just above the Early February Crust produced numerous avalanches over the past month.  A recent public observation from the White Pass backcountry indicates that these layers are still reactive in snowpack tests. Widely breaking avalanches were spotted from Crystal Mountain on Monday in Mt. Rainier National Park and could have failed at this interface. Wet slab avalanches are confirmed to have failed on these layers just across the Cascade Crest in the East South over the weekend. While you aren’t likely to trigger these slides, a cornice fall or wet loose certainly could. Any avalanche occurring on these weak layers would be 3-6+ ft deep, very wide, and likely unsurvivable. 

    (3/18/2024)

    A widely breaking avalanche in Mount Rainier National Park. It likely occurred on 3/18 and may have broken on persistent weak layers.

    Smaller wet avalanches can be see in the foreground. 

    Photo: Crystal Mountain Pro Patrol

Avalanche Discussion

Tuesday is the first day of spring, but it will be the last day of what has felt like summer. Multiple nights above freezing, daytime temperatures soaring into the 50s and 60s, and little wind have resulted in a multi-day wet avalanche cycle. Over this warm spell, avalanche activity has waxed and waned, peaking at different times in different locations. The avalanche character has shifted throughout this period as well. Rollerballs and pinwheels, wet loose avalanches, slabs, and cornice collapses have all been reported during this warm-up.

On Monday, Crystal Mountain Pro Patrol reported skier-triggered wet avalanches gouging into old snow layers and widely propagating natural avalanches in Mount Rainier National Park. Similarly, White Pass Pro Patrol reported increased loose natural avalanche activity in the surrounding backcountry.

Wet avalanche cycles like this are the most challenging forecast we make. There is no simple observation to let you know the scales are tipping, and often, the danger remains elevated for days. All of these factors make managing these conditions very difficult for backcountry travelers. Avoidance becomes the primary tool. 

Temperature inversions may result in a firm surface crust at lower elevations in the morning, limiting activity. Keep an eye on the terrain above you - it will already be baking in the sunshine and will be more prone to avalanche activity. 

Regions covered