Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Following Tuesday night's deluge, the avalanche danger is limited to more specific terrain features. Glide avalanches linger on steep, poorly supported bedrock slopes and beneath cracks in the snowpack. If you make it above the rain-snow line, expect dense snow and shallow drifts that you can trigger in the lee of ridgelines.

Avalanche problems

  • Glide Cracks

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2

    3-4" of liquid water increased the number of cracks on steep and poorly supported bedrock slopes. These are the areas you should treat with suspicion on Thursday as water continues to drain the snowpack and lubricate the underlying bedrock features. These slopes should be easy to identify during periods of good visibility, but you might have to anticipate where they might exist as cloud, rain, and higher elevation snow return to the West North. Simply limit your exposure to terrain in and under the types of features in the image to avoid the potential for a large chunk of snow to surprise you. 

    The majority of the avalanche danger will be related to the wet snow problems lingering with this event. Rain rills throughout the landscape indicate that the snowpack is draining well and that additional rainfall expected on Tuesday is unlikely to impact the danger significantly. However, it still may be possible to trigger a wet avalanche on a steep or poorly supported slope if you sink in past your ankle. If you find, wet and poorly supportive conditions in your terrain, stick to slopes less than 35 degrees.

    (12/18/2024)

    Glide cracks and poorly supported wet snow on steep, rocky features.  

    Photo: Irene Henninger

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Dry snow will continue to fall at upper elevations on Thursday and it will increase along with moderate southerly ridgeline winds in the afternoon. Expect fresh and day-old slabs to form above a refreezing 12/18 crust. We expect a good bond to the crust, but it's worth verifying and checking slab reactivity with simple hand pits and test slopes once you reach dry snow. Anticipate and steer around steep and poorly supported slopes in the lee of ridgelines, particularly those that are actively wind loading, where you are most likely to trigger a small avalanche.

    Blowing snow will point you to the deposition zones you want to avoid.

    Photo: Joe Dellaporta

Avalanche Discussion

Mt Baker received 5" of precipitation, since Tuesday morning, with about 3" of this in the form of liquid. Heavy snowfall changed to rain below Heather Meadows early Tuesday and then snow levels jumped above 7000 ft during the evening hours. The combination of heavy snowfall and strong warming triggered a very extensive natural avalanche cycle in the Baker Backcountry. NWAC forecasters found crowns in the 2 ft deep range running on all aspects, in some cases down to the Bagley Lakes. We're not sure whether these released as storm slabs or wet slabs. See photos of the carnage in the gallery, including glide cracks on Mt Herman, along with a snow profile showing the moist snow down to below the 12/7 crust. You can see more detailed observations from Bagley on Wednesday (here and here).  Mt Baker Pro Patrol also reported isolated glide avalanche activity.

If you find firm surfaces early Thursday, long falls could be dangerous. So consider the consequences. These slick slopes may exist on wind-stripped slopes at upper elevations.

Rainfall may have blown out snow bridges and reduced the snowpack significantly below 4000 ft in some areas. 

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