Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

You can still trigger an avalanche in wind drifted snow at and above treeline. Identify and avoid areas where the wind created deeper, denser drifts to reduce the likelihood of triggering an avalanche. 

Avalanche problems

  • Wind Slabs

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

    Backcountry travelers in adjacent zones triggered a handful of small avalanches and one larger wind slab over the weekend. You could trigger one of these in very steep unsupported terrain like convex rollovers, above or around cliffs, and under cornices. Be on the lookout for rounded, pillowy-looking drifts perched over steep terrain. A few inches of new snow, moderate winds and less visibility on Tuesday could make areas of wind slab harder to identify and maybe build shallow new slabs.

    Snow pits and other quick tests might give you more information to judge stability. You can also just avoid the problem by using a lower angled line to navigate around suspect features. There is plenty of usable terrain where you won’t trigger one of these - you just need to identify the few places where it is still a very real possibility.

    Example of a drift and wind affected surface indicating the direction of loading.

Avalanche Discussion

The northern portion of the zone stayed clear through the weekend while the southern areas near Snoqualmie and Stevens saw more clouds, a few inches of snow and warmer temperatures. Some areas near the crest experienced strong easterly winds. Where there was sun, southeast through southwest facing slopes warmed enough to create rollerballs and even a few very small wet loose avalanches. While a hard breakable crust now coats solar aspects, shady slopes might still hold soft snow where not wind affected.

Snow profiles in neighboring zones show that near treeline there is generally 2-4 feet of settling snow over a crust. Below are alternating layers of rounding facets and hard crusts to the ground. Cold temperatures have likely drawn out both the settlement and rounding processes compared to average conditions. Weaker interfaces between recent storm and wind slab layers usually bond quickly - with the typical near freezing temperatures. Currently, the same layering appears to be staying weaker for longer in this colder weather pattern, especailly in the north and near the Cascade crest where temperatures have consistently stayed cooler..

The current structure is not yet alarming and may never be a widespread problem. A lack of consistent avalanche activity demonstrates the snowpack is mostly handling the current load. On the other hand it’s not a status quo snowpack for early December. Keep this in mind and take the extra time to investigate and get a feel for the snowpack where you travel. 

Regions covered