Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

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

You can expect wet avalanche activity on steep, south-facing slopes on Tuesday. We're not quite sure how many and how large avalanches will be, but steer around steep south-facing slopes and the terrain beneath them when you notice snow getting moist or rollerballs starting to come down. Shady aspects are holding onto dry snow and shallow avalanches could still occur in steep pockets, especially at upper elevations. 

Avalanche problems

  • Loose Wet

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

    Freezing levels will rapidly bump up to 8500ft Tuesday afternoon, which will probably mean a spike in wet loose avalanche activity during the day. Partly cloudy skies with increasing afternoon sky cover and the weak December sun leaves us with uncertainties about how much avalanche activity will actually occur. That being said, wet loose avalanches are some of the easiest type of avalanches to predict and manage.

    Rollerballs are sometimes precursors to wet loose avalanches. If you see rollerballs, and especially if you see new or active wet loose avalanches, avoid traveling on steep aspects or the lower angle terrain beneath the steep slopes. Snow that was previously light, dry powder usually surprises us the most, as it doesn't take much warming and moistening before rollerballs and then small wet loose avalanches begin running in the shallow surface layers. We expect any activity to run in the new snow layer, probably 6 inches deep or less. 

    Slopes may not be reactive first thing in the morning, but as the day warms up, or if more sun patches appear, wet activity could increase. Expect more easterly aspects to moisten in the morning, before shifting south, and then more westerly in the afternoon. Avalanches also tend to first run near rocky patches and cliff bands, or they could possibly be initiated from snow falling out of trees. 

     

    (12/9/2024)

    Wet loose avalanche activity from the Baker backcoutry on Monday: Only small amounts of rollerballs and slides ran from rock bands on steep, south-facing terrain. Expect more activty on Tuesday. 

    Photo: Toby Swimmer

  • Storm Slabs

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

    We received just over a foot of new snow Saturday night, and avalanche activity peaked early Sunday morning. At mid and upper elevations, it's possible that you could still find and trigger an avalanche in steep locations. Very little wind occurred during and after the storm, but in some areas, especially at upper elevations where we have minimal information, you might find a subtly stiffer pocket of snow that you could trigger an avalanche in. Any slabs will likely be about 6 inches deep. 

    If you do trigger a slab avalanche, it may be hard to identify beforehand as the slab could be so soft. However, especially at upper elevations you might see subtle wind sculpted features as good indicators of slab formation.. If you enter steep terrain with loose, dry snow, you could initiate a sluff, or dry loose avalanche. Any loose dry avalanches will likely remain small, but pay attention to your surroundings if you enter steep terrain. These avalanches will usually fan out below you, but if you're not paying attention and get ahead of it, one could hit you from behind. 

    If you enter steep terrain on Tuesday, expect that a small slab or sluff could result, and have an exit plan or strategy so that if you do trigger one of these avalanches, it won't take you for a scary ride. In particular, if you're above terrain traps such as a gully, a cliff, trees or boulders, make sure you've got an escape plan so you don't get buried deep in  a gully, taken off a cliff or dragged through objects. 

    Example photo: slabs that you can trigger may still exist on steep rollovers. This one is on a small test slope, but you might be able to trigger one a little larger than this. 

    Photo: Hans Brubaker

Avalanche Discussion

Snow that fell Saturday night mainly appears to be well bonded to the underlying crust. The crust formed from the 2 inches of rain that fell in the day before the snowfall began. Under the crust, moist, consolidated snow exists. Most of our avalanche concerns lie within the new snow layer above the crust. However, in the week of high pressure before the snow and rain, many large glide avalanches surprised us throughout the West North zone. We believe that most glide avalanche activity has backed off as water has drained from the snowpack, but it's not completely out of the question that one might still happen. Consider avoiding traveling below large glide cracks to avoid this unlikely situation. 

Observations are limited this time of year. We have very little information from upper elevations, in particular. Help us write a better forecast by sharing an observation if you get out in the backcountry. 

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