Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Around a foot or more of snow has fallen in the zone and you can trigger avalanches in the storm snow layers on steep slopes. Steer around steep slopes near and above treeline, giving the snowpack time to adjust. You may also see small loose dry avalanches running on steep shaded slopes, and as the sun shines intensely on southerly slopes, small wet loose avalanches may occur. 

Avalanche problems

  • Storm Slabs

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

    Near and above treeline has about a foot or more of new snow, and you could trigger an avalanche on steep slopes in the new storm layers. These avalanches could run as deep as the new layer. Snow is continuing to fall through much of Monday night, so give steep slopes time to adjust to the new load. You can expect snow to be more reactive in wind-loaded areas as you make your way towards the alpine. Use small test slopes and hand pits on the relatively shallow storm layers to determine how well the layers are bonding to the older snow beneath them. If you encounter long shooting cracks, whumphs, or recent avalanches take them as clear warnings to avoid steep nearby terrain. Your best plan for the day is to avoid travel on slopes steeper than 35 degrees while the snow adjusts. 

    Since the storm ending on 2/7, avalanches have been triggered on a slightly weak layer above a crust in both the West North and Stevens Pass zones, failing around 2 feet deep, beneath last week's storm snow. I've dug several pits in both of those zones in the last week, without finding alarming layers of concern in those pits, yet we still infrequently have avalanches failing here. One was reported in the West North zone, remotely triggered by a snowmobiler late Saturday, and another also occurred that day at Stevens Pass, which involved a partial burial. This layer is spooky, and we don't expect it to go away overnight. Clearly, it's difficult to find in pits. This also isn't an avalanche we want to get caught in. They've occurred near and above treeline on wind-loaded slopes. For now, if you choose to travel into steep near and above treeline wind-loaded areas be aware that there is a very small chance you could trigger an avalanche on this layer. 

    You could trigger an avalanche as a slope rolls over and gets steeper, like in this photo.

    Photo: Adam U

  • Loose Wet

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

    The sun will be shining in full force on Tuesday. Temperatures will remain cool, but we expect small wet loose avalanches to occur on steep slopes. Wet avalanche activity will likely shift during the day from easterly to south, and finishing on westerly slopes. You might end up only seeing rollerballs, or subtle moistening on snow surfaces. Evaluate the snow surfaces as you travel, and if snow starts getting sticky and heavy and rollerballs are running in abundance, keep in mind that wet loose avalanches in the previously dry low-density snow could follow. Start shifting your travel plans away from steep slopes on those aspects when wet loose avalanches start happening. 

    Dry loose avalanches could also run on steep, non wind-affected slopes. They could run naturally in very steep shady areas, or as the sun first hits some sunny slopes. You could also trigger small sluffs, or dry loose avalanches, if you make your way onto steep slopes. 

    Rollerballs like this are often indicators that the snow surface is becoming weak and wet loose avalanches may soon follow.  

    Photo: Robert Hahn

Avalanche Discussion

Southerly portions of the zone picked up more snow than the northern part of the zone. About 1-1.5" of water fell throughout the zone, and over half of the water started out as rain below 4000ft. A crust is likely present beneath the new snow layer up to about 5500ft. Above 6000ft most of the water fell as snow. Depending on where you are, avalanche danger may be different from the forecast, so be prepared to make your own assessments. 

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