Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

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

Expect natural and triggered wet avalanches, especially on steep, sunny slopes. Very warm temperatures and sun will melt and weaken the snow surfaces. If you hit the wrong spot, you could trigger a large and surprising slab avalanche on shaded, northerly aspects.  

Avalanche problems

  • Loose Wet

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

    Natural avalanches are most likely on sunny slopes and you may even be able to trigger slides on shadier aspects, though they will be small. There's enough soft snow near the surface that wet avalanches could be big enough to bury you on large steep slopes, especially at middle and upper elevations. Rollerballs, snow falling from trees, and fresh avalanches are all signs that you should move to more shaded or lower-angled terrain. Even small wet avalanches could be forceful enough to push you into trees or over cliffs. The very warm temperatures and plenty of natural wet avalanches are maintaining concern for triggering old weak layers buried well below the surface. 

    (2/5/2022) Rollerballs and small wet loose avalanches on a steep east-southeast aspect, 4,400ft. Stevens Pass. Photo: Josh Hirshberg

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2

    Continue to use caution and consider avalanche terrain on the north half of the compass guilty until proven innocent. There's still a chance that you could trigger a surprising slab avalanche that could break widely across a slope. Use extra caution on leeward sides of ridges that hold fresh drifts from northwest winds on Friday night. Watch for "red flag" signs like whumphing collapses, cracks shooting through the snow, and tests that propagate or fail suddenly. If you see these indicators, stick to slopes less than 35 degrees and avoid traveling in or under large avalanche paths and steep slopes. Put plenty of space between where you travel and big terrain features.  

    The late January weak layer can be found 1.5-2ft below the surface. Weak sugar-like facets (or surface hoar) sit above, and sometimes between, a crust. We have the best information that you can trigger these avalanches on NW-NE aspects between 4,000ft and 4,700ft. This low elevation band produced startling collapses and shooting cracks earlier in the week. There is uncertainty with higher elevation, alpine terrain. Saturday was an active day in the West North zone, where backcountry travelers triggered large persistent slab avalanches on the same layer that exists in this zone.

    A large snowmobile triggered avalanche that released on late January crust-facet layers. NE aspect at 5400' Excelsior Peak. In the West North zone. 

    Photo: Graham Clark

Avalanche Discussion

Rollerballs and wet avalanches have been reported on sunny slopes and at lower elevations in the past 3 days. We still have a good bit of uncertainty about the complex late January weak layer. Observers targeting it on northerly aspects have reported variable results with some tests indicating the potential for triggering persistent slabs (Saturday, Skyline Ridge) and some stable test and profile results. There are signs that at mid-elevations the weak layer is rounding and strengthening, though there are still some slopes holding weak snow. On Thursday, explosive testing at Stevens Pass Mountain Resort produced no results on east through south aspects from 4,800 to 5,000ft. Earlier in the week, observers reported shooting cracks or whumphing collapses on northerly aspects in the low 4,000ft elevation band (Stevens Pass proper, Yodelin, and Henry Creek clearcuts).  Information is limited above 5,600ft. 

In late January, near-surface facets and surface hoar were found on a variety of shaded, northerly slopes, especially below 4,700ft. Warm temperatures and mixed rain/snow on the 30th may have melted these weak layers in some areas at mid-elevations, but perhaps not all. Approach the backcountry with an assessment mindset and be ready to stick to lower-angled terrain. Check out the other recent observations from Henry Creek, Upper Nason creek, and the Stevens Pass sidecountry. Let us know what you find, and if you experience whumphing collapses or shooting cracks to better track these tricky conditions. 

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