Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

You could still trigger avalanches in wind-drifted snow or where you find a weak layer below the recent snow. While the likelihood of avalanches decreased, the consequences have not. With these tricky, lingering problems, you can enjoy travel on  slopes under 35 degrees and in simple terrain. 

Avalanche problems

  • Wind Slabs

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

    Avoid steep slopes on leeward sides of ridges, the base of cliffs, and cross-loaded terrain features. You may hav to probe or feel for the stiffer wind-drifted snow just below the surface. Cracks shooting out from your equipment are another key sign that these wind slabs are unstable. 

    We have a lot of uncertainty, particularly at the upper elevations, about the distribution and reactivity of this problem. The very weak snowpack structure has largely kept us and other observers out of upper elevation and wind-drifted slopes. Simply avoiding steep wind-drifted slopes is the best way to manage the complex conditions. 

    (1/11/2025) Crown of intentionally triggered windslab, NW ridge Tye Peak. Photo: Ryan Minton

  • Persistent Slabs

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

    Whumping collapses are a bullseye sign of unstable snow, and the best clue that you should stick to terrain under 35 degrees. Keep a large margin away from steeper slopes. Consider avoiding steep terrain on the north side of the compass, especially in sheltered areas like open, gladed slopes. Smaller storm slabs and fast-moving, dry-loose avalanches still exist throughout the terrain. These problems are more straightforward but could break into a wider more dangerous avalanche. This adds to the complexity of our snowpack. 

    Under the recent snow is a wide range of surfaces formed from the January Drought Layer. The most consistent weak layer is well-developed facets on shaded northery slopes. You might also find pockets of huge surface hoar in deep valleys and sheltered terrain. Many slopes don't have much of a cohesive slab over these persistent weak layers. This makes it a tricky problem to pin down and also one that won't be quick to go away. As the storm snow gains cohesion, the problem may get worse . The safest terrain management option for this problem is avoiding it altogether by staying on low-angle terrain or moving to other aspects. 

    (1/19/2023)

    An example of a persistent slab in gladed terrain, like you might be able to trigger.

    Photo: Ryan Minton

Avalanche Discussion

The main takeaway from the current snowpack is that it is very weak, and it's nearly impossible to determine where you might run afoul of a persistent slab avalanche. Avoid a "stepping out" midset, until we get a better understanding of this complex snowpack. Broken clouds and small amounts of sun on Tuesday may have allowed the recent snow to gain cohesion. 1-2ft of recent snow fell on widely varying surfaces. Stevens Pass Ski Patrol and WSDOT avalanche forecasters reported mostly small storm slab avalanches, with a few larger wind slabs, releasing on the old surface or within the new storm snow. The new snow fell at very cold temperatures and lacked cohesion, so backcountry users reported more dry loose avalanches than slabs. Another observer reported a propagating extended column test on a layer of faceted snow, and observers throughout the zone reported widespread collapsing. Overall, the results are mixed, but we're concerned with lingering instabilities on the January Drought Layer (JDL) on these northerly aspects. 

An NWAC Forecaster was in the Henry Creek Area on Sunday to check on the state of our weak snowpack. Traveling through the low-angle clearcuts, they experienced numerous localized collapses and found two layers of concern in snow profiles. The deepest layer is buried 20-23in down and consists of 1-2mm faceted grains over the 1/10 crust. Above that, buried 15-20in, is the surface of the January Drought Layer, which is 1cm buried surface hoar over another layer of 1-2mm faceted grains. I also observed a deep crown on a steep southern aspect at 5700ft, likely a wind slab that occured during strong winds on Saturday. 

You can help us build the forecast by submitting an observation HERE or via the Avy App. 

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