Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Springtime weather could produce wet avalanches on steep and sunny slopes Friday. If the snow surface becomes soft and moist, you’ll know that the time has come to put these slides on your radar. They may be the trigger needed for larger and more surprising avalanches in isolated terrain. 

Avalanche problems

  • Loose Wet

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

    Continued sunny and unseasonably warm weather will attempt to destabilize the snow surface on Friday. A change from firm and icy to wet and sticky snow may be your first indication that Wet Loose avalanches are possible. If you are sinking into the snow deeper than your ankle, or notice precursors to wet avalanches such as rollerballs and pinwheels, it may be time to head for shadier terrain. Wet Loose avalanches will be more likely on slopes over 35 degrees that see direct sunshine and often start at a point before fanning out and growing in size as they descend. These avalanches could initiate more easily in shallow areas of the snowpack, such as near rocks and cliffs and should be larger and easier to trigger as you ascend in elevation. 

    Rollerballs are great indicators that a wet loose avalanche could follow.  Photo: Andrew Kiefer

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    The weak snowpack structure that has produced recent persistent slab avalanches in and around the zone remains in place. The last reported avalanche on this layer was in the neighboring West North zone on Tuesday (2/8). The distribution and likelihood of triggering these avalanches are hard to pin down, but generally speaking, they are more likely at upper elevations on aspects that do not receive direct sunshine. You need to take the time to dig in the snow with your hand or shovel and investigate this layer before committing to a slope. Persistent slab avalanches can fail in surprising ways by breaking above you or wider than you are used to, sometimes connecting terrain features. When in doubt, avoid slopes over 35 degrees where you suspect this layer could be a player.

Avalanche Discussion

Thursday night will be another night of above freezing temperatures, but the skies should be mostly clear. This could help the surface to freeze from the top down and possibly help with stability first thing in the morning. Our expectation is that this stability will be short-lived and the snow surface will eventually soften enough to become unstable. You will need to see how the weather is unfolding in your location and then look at the snow surface to determine the likelihood of triggering a wet avalanche on the slope you are on. Surface conditions are variable across the zone, and dependent upon aspect, elevation, or the presence of sunshine. 

All avalanche activity should remain above the Late January Crust that can be found around a foot below the surface. Most slides should involve the surface snow, but a large trigger such as a collapsing cornice or even a descending Wet Loose could be enough to trigger the deeper persistent grains. Choose safe travel routes that put plenty of space between you and hanging blocks of snow and ice. Be sure that you have plenty of terrain options to escape increasing danger throughout the day and the potential for larger avalanches. Of course, if you travel into larger and more consequential alpine terrain, the potential for larger and more consequential avalanches goes hand in hand with your decision.

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