Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Human triggered avalanches and signs of unstable snow were reported recently throughout the West North Zone. Avoid wind drifted slopes 35 degrees and steeper at upper elevations, especially where an avalanche could carry you into rocks, trees, cliffs, or other obstacles. Use caution as the icy old snow surface below the recent snow is a good sliding surface for avalanches and still makes for slick and challenging travel conditions. 

Avalanche problems

  • Wind Slabs

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

    You can trigger an avalanche in wind drifted snow large enough to bury, injure, or kill a person. Pay attention as you transition into wind affected terrain and look and feel for sudden changes in snow surface texture and hardness. Previously formed wind slabs still need time to stabilize, and fresh slabs could continue to build Friday. You may find wind slabs on a variety of aspects and in unusual locations due to shifting winds over the past week. Fresh slabs rest atop variable surfaces including icy crusts and weak, sugary snow. Look for obvious signs of instability like recent avalanches, shooting cracks, and collapses (observation, observation). Carefully assess how recent snow has bonded to old snow surfaces as you travel using hand pits and small test slopes. Seek out lower angled and wind-sheltered terrain to reduce your risk of triggering an avalanche. 

    (1/28/2021) A skier triggered avalanche in new/wind drifted snow that broke about 1ft deep and ran on a crust layer. The avalanche occurred on a NW aspect at 4300ft in the Twin Sisters range. Photo: Matt Lubar

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    The recent cold, low-density snow will see sunshine for the first time this week with periods of clearing skies mid-day Friday. Snow surfaces may quickly become wet and weak on steep solar aspects. If you see trees shedding snow, or rollerballs and pinwheels, expect wet loose avalanches to follow. Although these avalanches may be small, they could knock you off your feet and carry you into trees, rocks, cliffs, or other obstacles. They may even trigger slab avalanches as they run downslope. Watch for changing conditions throughout the day, and move to shaded or lower angled terrain to avoid the problem. 

    (12/2/2020) An example of rollerballs and pinwheels on the east aspect of Table Mountain near 5500ft.

Avalanche Discussion

Since Sunday, 12-16in of new snow gradually accumulated in the Mt. Baker area. Strong and shifting winds accompanied this incremental load of cold, low-density snow creating variable loading patterns. Natural and triggered avalanches to destructive size 2 were reported recently in many areas including Mt. Herman, Swift Creek, Glacier Creek, Schriebers Meadow, and the Twin Sisters range. Avalanches occurred on upper elevation, wind-loaded slopes breaking 6-24in deep on the slick underlying crust and within new and wind drifted snow.

Carefully assess the snowpack as you travel, especially on the northern half of the compass where you might find layers of weak faceted snow associated with two prominent crusts buried 1-2ft by recent and windblown snow. These layers were the culprit in a couple of recent avalanches (D1), including one remotely triggered by a skier (observation). Shooting cracks and collapses were also observed, along with sudden and propagating fractures in snowpack tests (observation). There is uncertainty regarding the distribution and sensitivity of these buried weak layers. Evidence exists but is not always easy to find. Weak snow could be above and below the crusts, or not present at all. The variability may be the biggest challenge, so investigate each slope you plan to ride individually, as what you find in one area may be different from the next.

The new snow is improving riding conditions following a period of cold, dry weather January 17-24, but firm and icy conditions still linger. At low elevations, the snowpack is still thin, with plenty of non-avalanche hazards present like open creeks, downed trees, and icy trails. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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