Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

Stay alert for drifted snow that will continue to form with southwest winds. These are most common below corniced ridgelines and in gullies where the snow surface shows evidence of wind effect. Wind-protected terrain offers safe and fun riding.

Avalanche problems

  • Wind Slabs

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

    Southwest winds returned yesterday after a brief cold front brought northeast winds. Observers noted 2 to 4 inches of snow available for transport in upper elevations. This snow will continue to build into thicker slabs near ridgelines and cross-loaded features. Paying attention to changes in snow density will key you into places where wind slabs exist.

    The older generation of wind slabs appears stubborn; however, don’t be lulled into trusting older slabs. In steep terrain, avoid riding on pillows of dense, thicker snow. You can avoid the problem by choosing terrain where the snow is sheltered or scoured by the wind.

    (2/15/2023)

    Blowing snow observed in the Flathead Range.

    Photo: gz

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3

    Weak layers of buried surface hoar and facets exist 2 to 4 feet below the surface in the Swan Range. You can avoid this problem entirely by sticking to slopes with lower slope angles. If you step out onto steeper slopes, avoid convex rollovers where you are more likely to trigger a slide. Even small avalanches have the potential to step down to buried weak layers. Choosing slopes with runouts free of trees and cliffs is a way to reduce your chances of trauma if the unexpected happens. Conservative terrain choices and a wide margin of error is the way to manage this problem.

     

    (1/31/2023)

    Snowpit on SE aspect in the Swan Range.  Failed on a persistent weak layer 50cm from the surface,  ECT20.

    Photo: sw

Avalanche Discussion

Yesterday, riders found several inches of cold, dry snow from the recent underperforming storm in the Swan Range and up to six inches in the Flathead. Southwest winds transported light amounts of snow above 6000 feet. Saturday’s warm temperatures and sunny conditions left a crust on all aspects up to 5000 feet and up to 7000 feet on southerlies. Sluffing in the new snow was the only instability noted. 

A dedicated observer in the Swan Range noted no propagation on a buried layer of surface hoar in snowpit tests at his snow study plot. This is the first time without propagation in a long time and hopefully a sign of healing and strengthening of this pesky layer.

Today, extended periods of solar radiation may develop loose snow instabilities on sunny slopes. Tree bombs falling from branches, snow peeling off rock faces, and rollerballs are all precursors to loose slides. If loose snow slides develop, they may travel long distances due to the underlying crust. Stay ahead of the sun during your travels and limit time spent underneath south and west aspects this afternoon.  

Regions covered