Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

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

There's still a chance that you could trigger large and dangerous avalanches where you find hard over soft layering 1.5-2 feet below the surface.  A more likely scenario will be triggering small loose avalanches in the surface snow. With an abundance of cohesionless, dry snow and even sunnier skies, these avalancheches may be easy to trigger on Friday.

Avalanche problems

  • Loose Dry

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

    Watch for natural loose avalanches especially on steep, sunny slopes as skies clear. Snow falling from trees or rocks could intitiate these slides. While we don't expect natural avalanches elsewhere, you can trigger them easily, especially 40 degrees and steeper, or above unsupported features like rocks and cliffs. You can use small, inconsequetial test slopes to see how easily the snow slides.

    If you're in terrain that overlaps with Persistent Slab distribution, you need to manage the risk of that, more dangerous, problem. On those slopes, you won't be able to simply avoid surface instabilities.

    (2/6/2025)

    Small natural and skier triggered loose dry avalanches. Moonlight, ESE, 4,600ft

    Photo: Joe Dellaporta

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    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. The most problematic areas could be where the westerly wind formed stiffer slabs on leeward slopes last weekend at middle and upper elevations. The safest option for this problem is avoiding it altogether by staying on low-angle terrain or less problematic aspects. Keep a large margin between where you travel and suspect slopes steepr than 35 degrees.

    The problematic snowpack structure is where you find the recent snow at 4 Finger hardness or greater with an underlying weaker layer of sugar-like facets (or surface hoar). This January Drought Layer (JDL) will be about 2 feet under the snow surface. To find the older drifted slabs from west and southwesterly wind, you'll need to probe or dig to feel for them. These stiffer slabs will likely be under softer, more recent snow. Many slopes don't have much of a cohesive slab over these persistent weak layers. In these locations, you could trigger larger loose avalanches. 

    (1/19/2023)

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

    Photo: Ryan Minton

Avalanche Discussion

On Friday, we expect slightly more warming of the snow surface. Temperatures will nudge above 25F degrees and skies should be the clearest we've seen this week. This could  warm snow surfaces enough for more loose avalanches. On Thursday, observers reported small natural and triggered loose dry avalanches on steep, sunny slopes. By afternoon, these aspects formed a thin crust.

While we don't have many observations of Persistent Slab avalanches in the Stevens Zone, there have been many in other zones to the north and south. From the 31st-2nd, about 2ft of snow fell on widely varying surfaces. In the days since, light snow has gradually accumulated to total another 9". The new snow fell at very cold temperatures and lacked cohesion. While many tests and observations show a lack of slab cohesion, we remain concerned with lingering instabilities on the January Drought Layer (JDL) on northerly aspects. Observers have reported many whumpfing collapses, as recent as the 5th. Both the sun and time since the storm of January 31st are allowing slabs to slowly gain cohesion, setting the seen for more consistent slab-weak layer structure. Theses peristent slabs could become more problematic with the next significant snowfall. The main takeaway from the current snowpack is that it is weak, and it's difficult to determine where you are more or less likely to trigger persistent slab avalanches. Avoid a "stepping out" mindset, until we have better confidence with these tricky conditions.

An NWAC Forecaster was in the Henry Creek Area on Sunday. 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 15-20", is the surface of the January Drought Layer, which is 1cm buried surface hoar over another layer of 1-2mm faceted grains. There was also a deep but narrow 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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