Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

Deep new snow and strong winds will sharply elevate the risk of triggering an avalanche.  Avalanche danger should peak overnight, but higher danger of human and naturally triggered avalanches could persist if heavy snowfall and strong winds continue through the morning. 

Avalanche problems

  • Storm Slabs

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

    On Wednesday limit your exposure to avalanche terrain and stick with lower angled slopes. You could trigger avalanches in steep, sheltered terrain. You are more likely to trigger one in wind loaded terrain where there are thicker, more reactive slabs. Natrual avalanches could occur with intense wind loading or during periods of very heavy snowfall.

    Stay in tune with the terrain around you and assess new snow layers as you travel. Are you experiencing shooting cracks? Seeing natural or human triggered avalanches? Is there a  layer of denser or wind drifted snow over lighter snow below? Is it snowing so hard that you can't see the terrain around you? All are signs that it’s time to be more conservative when picking what terrain you travel up, down or across. 

    Many areas below treeline still don’t have enough snow to produce avalanches - but some slopes are starting to fatten up in that elevation band. Stay alert to steep terrain with smooth snow cover where you can now trigger avalanches.

    (4/5/2022)

    Natural storm slab avalanche in deep new snow last season. 

Avalanche Discussion

Forecast precipitation amounts for the incoming storm are not record breaking, but below normal temperatures could produce much lighter, deeper snow than we normally experience. 1.75” to 2.50” of snow water equivalent (SWE) should easily produce 2’ to 3' of feet of snow.

Conventional wisdom says such light density snow should not make much of a slab and that could be the case Wednesday. On the other hand subtle differences in temperature, precipitation intensity and wind speed (even in terrain not experiencing direct wind loading) could still produce a slabier layer over weaker snow. 

The 1' to 2' of most recent snowfall sits on a strong snowpack of rounded grains, melt forms and crusts. A big load from the approaching storm should test a lingering weak layer - surface hoar and facets from November’s drought - that might still exist in colder and/or higher elevation terrain. 

Finally . . . don’t let deep new snow make you forget it's still early season out there and the snowpack is still shallow. Many hazards remain including exposed or barely buried trees and rocks, open creeks and other rugged terrain features.  

If you are out and about in the mountains, let us know what you find by submitting an observation.

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