Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

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

Avalnahces are difficult to trigger, but the consequences could be significant where you find hard over soft layering 1.5-2 feet below the surface.  Subtle wind drifting could add to slabs at upper elevations. For Sunday, expect continued cold temperatures, partly cloudy skies, and just enough west wind overnight for light wind transport.

Avalanche problems

  • Persistent Slabs

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

    While there are no known avalanches in this zone associated with persistent weak layers, the snowpack structure doesn't inspire confidence. Due to the potential consequences of triggering a large avalanche, we can't conclusively say that conditions are "generally safe." The most problematic areas could be where the westerly wind formed stiffer slabs at upper elevations. If you encounter whumpfing collapses or shooting cracks, stick to terrain under 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. Many slopes don't have much of a cohesive slab to be problematic over these persistent weak layers.

    (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 Saturday, 3-4" of snow accumulated and west winds picked up just enough for some wind drifting. More light transport may occur overnight, but winds should taper Sunday morning. On Thursday, observers reported small natural and triggered loose dry avalanches on steep, sunny slopes. By afternoon, these aspects formed a thin crust, that's now under the most recent snow.

From the 31st-2nd, about 2ft of snow fell on widely varying surfaces. Another 1 foot of snow accumulated slowly in small increments over the past week. 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 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. While we don't have many observations of Persistent Slab avalanches in this zone, there have been plenty elsewhere. Locally, observers have reported a "scary" snowpack structure. It's now waiting for the right load to become more active, which may take some time. Theses peristent slabs could become more problematic with the next significant snowfall. 

An NWAC Forecaster was in the Henry Creek Area on the 2nd. They experienced numerous localized collapses and found  layers of concern in snow profiles. 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. 

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