Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

Mon
Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Surface hazards remain your primary concern at low and middle elevations. Even though we have generally safe avalanche conditions, keep in mind that patches of buried weak layers lurk in the snowpack above 6500 feet. Continue practicing safe travel techniques.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2

    Triggering an avalanche on a buried weak layer 2-3 feet below the surface is a low-probability, high-consequence problem. The early December rain destroyed the weak layers or capped them with a crust in many locations. Buried weak layers appear best preserved on wind-sheltered slopes that are shaded and face NW-NE-E. The only way to recognize that the slope you are on is suspect is to dig down and verify what’s underneath your feet or machine. Clear signs of instability, such as collapsing or whumphing, may not be present. Choose slopes where you find a robust crust or default to lower-angle terrain. 

    (12/16/2023)

    ECTP20 down 16 inches on the 12/1 surface hoar just below the 12/7 crust. 6800' N aspect.

Avalanche Discussion

Avalanche activity in our forecast area mirrors our mild weather.  The most notable avalanche reported in the past week was a skier-triggered thin wind slab in a sheltered chute (Noisy Basin observation). Besides this avalanche, activity has been limited to roller balls and generally small, wet loose slides on sunny slopes above the thick inversion status layer.

Winds capable of transporting snow picked up yesterday (Saturday) at many of our ridgetop weather stations. An experienced ski tourer reported moderate to strong winds at ridgetop locations on Mt Furlong in the Flathead Range. Although most observers noted a surface melt-freeze crust, there may be a lingering chance of isolated pockets of wind-drifted snow along exposed ridges and in the tops of chutes. 

The high-pressure system continues to create valley inversions. Challenging riding and skiing in the Flathead has limited observations. Due to this, we are uncertain about the distribution of the Persistent Slab problem in shaded upper elevations. For example, Rob found buried surface hoar with propagating results at Sixmile in the Swan, while I did not find any buried weak layers in central Glacier Park. If you are getting into terrain above 6500 feet, dig into the snowpack and let us know what you are seeing (link to submit observation).

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