Lawinenlagebericht

Swan Range

Flathead Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 5 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Expect wet snow avalanches to develop as sunshine and warming temperatures melt the snow surface. Pay attention to changing conditions and move to a different aspect or lower-angle slope if you find yourself sinking into mushy snow. Slabs formed during the recent storm may still be reactive to a rider's weight and should be evaluated before committing to a slope. 

We will issue our last daily Avalanche Forecast of the season this Monday, April 6th. General Avalanche Information updates will be issued on Tuesdays and Fridays through May 1.  

Lawinenprobleme

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2

    Today’s warming temperatures and the strong April sunshine will melt the surface snow and trigger wet snow avalanches. Most of the forecast area picked up one to two feet, or more, of snow during the recent storm. In many locations, this dense, heavy snow rests on a stout, slick crust that may inhibit bonding and allow slides to travel farther than anticipated.

    Look for snow falling from tree branches or peeling off rock outcroppings as one of the first signs of warming. Fields of rollerballs are often a precursor to the onset of wet loose slides. Sun-baked slopes will likely be the first to fail naturally, but a rider could trigger a slide on any steep slope.

    Stay ahead of the sun and move to a shaded aspect or a lower slope angle to mitigate this problem. Plan ahead so you are not stuck traveling beneath slopes sizzling in the afternoon heat. If you find yourself sinking into manky snow, you have overstayed your welcome.

    Storm Slab Avalanches

    Wednesday and Thursday's snow and west-to-southwest winds likely built thick slabs on all aspects at mid- and upper-elevations.  Warm weather is helping strengthen these, but some may remain susceptible to human-triggering.  Cracking in the surface indicates you have found a slab. Dense snow that your boards or machine don't penetrate is another clue. Default to lower-angle terrain for a safer experience.

     

     

    (4/6/2025)

    This image shows loose wet avalanches on sun-baked slopes. The rock outcrops on the left side of the image are likely trigger points, as the dark rock heats up from solar input.  

    Photo: Chris Gotschalk

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–3

    The well-advertised persistent weak layer still dictates our travel advice at upper elevations on slopes facing northwest to northeast to southeast. Fortunately, it is buried under supportable crusts and thick slabs that limit a rider's ability to impact this layer. The exception to this will be on slopes with varying snow depths, such as those on wind-swept terrain or areas peppered with rocks.

    Generally, a large trigger is needed to initiate a slide, such as a falling cornice succumbing to today's warmth. 

    The safest option remains avoiding the slopes where this problem exists. If you decide to ride in this terrain, choose slopes with a deep homogeneous snowpack where you limit the chance of affecting this layer.  

    (3/17/2026)

    This avalanche failed on a buried weak layer and was triggered by a smaller surface slide. The crown depth is impressive, and the potential size of slides triggered today. Photo: Michael Reavis

Avalanche Discussion

Friday's cloud cover and humid conditions moistened the snow surface on all aspects (image). Natural and human-triggered wet loose slides developed in the southern Whitefish Range (observation, observation), and we assume in other parts of the forecast area.  

Today's warming and sunshine will kickstart a weekend of wet avalanche activity. On some slopes, all of this week's bountiful snow may slide on the underlying crust, resulting in sizable avalanches. Fortunately, this problem is easy to mitigate by starting your day early, staying ahead of the sun, and moving to a lower-angle slope free of overhead hazard when the snow becomes wet. Natural slides are predictable: they begin on southeast slopes in the morning, transition to southerlies, and finally finish in the afternoon on west-facing aspects.  Human-triggered slides will depend on the quality of the snow beneath your feet or machine. I was on east and north aspects yesterday, where the snow was manky, and triggering a wet loose on a steep slope was a given. If you find yourself sinking into mushy snow that is no fun to ride, either move to a different slope or call it a day.

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This week—our last week of daily forecasts for the 2025–26 winter—we’re highlighting people, teams, and organizations that have contributed notably to Flathead Avalanche’s work and products, and supported the forecast team through a challenging and, hopefully, unusual winter.

FOFAC Education team:

Did you know there is a super cool program where the Valley's grade school classrooms travel to the WMR summit for a day of snow science and avalanche education? The FOFAC education team of Meg Killen and Clare George tag-teamed on this daunting task, introducing 450 students to a topic extremely relevant to kids growing up in a ski town. Their duties also included 90 in-class presentations at area schools. If that is not enough, they offered adult courses that included an evening session at FVCC and a field day in the southern Whitefish Range. Thanks to you both for a job well done!

Flathead Snowmobile Association (FSA):

The Flathead Snowmobile Association currently helps coordinate grooming and maintenance across more than 230 miles of snowmobile trails in the Flathead Valley. They play an integral role in avalanche education by offering scholarships to cover tuition for all FOFAC motorized classes, including Intro to Avalanches, Level 1, and Level 2. What an amazing service provided to the community! Thank you so much.

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Please take a survey!

Researchers Ian McCammon and Sara Boilen are developing new tools for to help backcountry skiers and boarders manage human factors. This survey asks about personal experiences with human factors and will take 7-8 minutes to complete. Thank you for your help!

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