Avalanche forecast

West Slopes South

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Highlights

You should find generally safe avalanche conditions thanks to a frozen surface and increasing clouds Thursday. Even still, you may see a few rollerballs or small wet slides near rocks and cliffs where the sun and warm temperatures can have the greatest impact.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    A decent overnight freeze will make the sun work a little harder Thursday to soften the snow surface. However, increasing clouds and strengthening winds should work to curtail the effects of sunshine and warming temperatures. As a result, we think any rollerballs and loose wet slides will mainly be limited to isolated areas near rocks and cliffs where the snowpack can warm faster. While these slides shouldn’t pose much of a risk, don’t let them catch you off guard if you’re traveling above a cliff or open creek. 

    During warm periods like this, trees and rocks often shed their snow. These “treebombs” can be a hazard on their own. You could also see cornices collapse and fail. While these waves of snow aren’t as large and widespread as we typically find this time of year, you still don’t want to be under one if it falls. Look for routes that help you minimize the time you spend under these looming features.

    (1/16/2023)

    Example: Rollerbalss from treebombs during a sunny period last week. 

    Photo: Pubic Observation

Avalanche Discussion

Despite warm temperatures, clear skies and a long mid-winter night should help the snow surface freeze. This means the sun will need to work extra hard to produce any wet unstable snow. Since we’re expecting increasing clouds and strengthening winds, it will be hard for this to happen. With all that said, this avalanche forecast hinges on the weather. A weaker freeze, fewer clouds, or lighter winds could all result in larger and more widespread wet avalanches. If you see lots of new rollerballs or slides entraining significant amounts of snow, then the scales likely tipped. Time to dial it back and seek out slopes not receiving direct sunshine. 

On shaded aspects at higher elevations, you may still find a lingering pocket of wind-loaded snow. A few days of mild temperatures should make these older slabs very hard to trigger. However, you may still cause an avalanche on a steep unsupported slope or convex rollover. Keep this on your mind before committing to rocky high consequence terrain. 

We’re mainly talking about surface snow issues in the West South zone. While there are older interfaces in the upper snowpack (1/21 and 1/18), we haven’t seen any recent slides on these layers. Generally, 1.5-2ft (45-60cm) of snow sits over the very prominent and stour MLK crust. At the moment we aren’t actively tracking any layers below this easy-to-find snowpack marker. 

On the southern volcanoes (Mt Adams and Mt St Helens) recent strong winds may have scoured slopes down to the icy MLK surface. This could cause slips to turn into uncontrolled falls. Make sure you have the tools and skills to manage these potentially very firm conditions.

Regions covered