Avalanche forecast

West Slopes North

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Slopes holding freshly wind drifted snow are where you could find an avalanche on Friday. Assess for instability before entering steep and consequential terrain. Anticipate challenging travel conditions on crusty or wind-hammered snow surfaces.

Avalanche problems

  • Wind Slabs

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

    The wind has been blowing and is forecast to continue in high alpine terrain. The real question is how much snow is available for transport to form fresh slabs. Southerly aspects are crusted over. Northerly aspects have already seen a fair bit of wind and may not have much loose snow lying around. An inch of snowfall likely didn’t do much to increase avalanche danger in most areas. 

    Pay attention to changes in snow depth and texture. Stomp on test slopes. wind lips and other features to gauge if wind slabs are still reactive. A bit of drifting snow will show you which slopes have seen some loading. Slabs that form over a slick crust can be surprisingly reactive. It's better to look for instability and find nothing than get surprised in just the wrong spot.

    Scoured snow surfaces can help identify pockets of wind slab. In this photo, the wind was blowing from right to left. In the surrounding area the slope to the right photo was rocky and wind scoured. The slope on the left was smooth with no texture.

Avalanche Discussion

Lingering instability in a layer of weak facets over the Jan 10th crust is still out there, albeit very isolated in distribution. Observers have noted big changes in layering at the crust over short distances. The faceted layer 6-12” down was observed as rounded on most slopes, but preserved and intact on a few others. Isolated whumping was also reported. 

You would be most likely to find this problem in terrain that has stayed colder in the last week, especially in the northern and eastern parts of the forecast zone. On the other hand, you are just as likely to find it in wind sheltered terrain as in more exposed areas. Fortunately, the layering in question is close to the snow surface and has been easy to assess with hand shears. If you find big granular snow grains at a clean shear then you probably found the problem as well.

Colder temperatures should make wet avalanches a thing of the past despite lots of sun in the week ahead. A firm crust tops the snowpack on sun-exposed slopes with a thinner crust on other aspects at low and mid elevations. All varieties of wind affected snow can be found in the alpine. Don’t expect much of a change in the coming week with high pressure in the extended forecast.

Regions covered