Bulletin d’avalanche

Flathead Range & Glacier NP

Flathead Avalanche Center
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Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
1 · Faible
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré last year. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

It is possible for a rider to trigger an avalanche on slopes where the surface has not frozen solid. Move off of and out from under steep slopes if you or your machine start breaking through the surface crust. Avoid traveling below glide cracks or cornice. 

Problèmes avalancheux

  • Wet Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1.5–3

    Recent rain and meltwater penetrated down to buried weak layers and caused large slab avalanches earlier this week. Cooling temperatures have helped to refreeze the surface of the snowpack. You can trigger a large wet snow avalanche where the surface crust has not formed or does not support your weight.  Today's rain and above-freezing temperatures could cause the crust to break down and make triggering more likely. Small loose wet avalanches are possible in the new snow and will entrain more debris on slopes without the crust. 

     Upper elevation slopes facing northwest, through east, to southeast harbored the weakest snowpack and may be slower to recover.  Likely trigger points include convex, unsupported slopes; wind-affected slopes with variable snow depth, or slopes peppered with rocks. 

    Cornices weakened during the recent warm spell and may continue to drop chunks onto the slopes below. Large tumbling blocks of snow can trigger an avalanche at the surface or deeper in the pack. 

     

    (3/28/2025)

    Wet snow on Red Meadow Peak failed as sluffs and slabs.  Triggering slabs of wet snow is possible where you do not find a supportable surface crust. 

    Photo: Flathead Avalanche Center

  • Glide Cracks

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    2–3

    An impressive amount of glide cracks have been reported across the advisory area. While cracks have been noted on all aspects and elevations, they appear to be concentrated on sunny slopes in the middle elevation band. Rain and meltwater moving through the snowpack increased glide activity and caused at least one glide avalanche this week. Cooler temperatures make glide avalanches less likely today. 

    The timing of glide avalanches is difficult, if not impossible, to predict. Do not dawdle below slopes where glide cracks are present. 

    (3/1/2025)

    This glide crack succumbed to the heat of the day Saturday, 3/1. The resulting avalanche was very large (D3).  

    Photo: Flathead Avalanche Center

Avalanche Discussion

Rain and meltwater penetrated deep into the snowpack during the last week. This produced a widespread cycle of wet avalanches, causing larger slabs to fail on buried weak layers. Cooler temperatures yesterday and overnight have helped to refreeze the surface of the snowpack. Below the surface, however, wet snow will take a little more time to stabilize. 

Snowfall has returned to the advisory area.  In general, accumulations are underwhelming (but still appreciated) with just 1 to 4 inches at most sites. Similar amounts are expected throughout the day.  It is unlikely new snow will be a driving force in today’s hazards except in areas favored by recent snow and wind. Two areas that come to mind are:

  1.  Central Glacier Park, where Flattop recorded 6 inches of snowfall in the last 24 hours
  2. The Swan Crest, where Aeneas Ridge recorded sustained wind speeds of 20 mph.

If you’re traveling in these areas, expect to find thin slabs of new and wind-drifted snow. Pay attention to new snow accumulations and look for signs of wind. Consider moving to less steep terrain if you find more than 8 inches of recent snow or notice wind-affected surfaces with a scalloped texture or dune-shaped features.

Fresh rollerballs and pinwheels are signals that new snow has become wet and can produce loose wet avalanches. These will be small in size where the new snow sits atop the recent melt-freeze crust. Slides can entrain more snow, become larger in size, or trigger large slab avalanches on slopes where the crust hasn’t formed or breaks down during the day. Treed or rocky slopes can be slower to refreeze.

Eastern Oregon University is conducting a survey to better understand avalanche safety preparedness among motorized backcountry users. The survey will help us learn more about who is purchasing and practicing with avalanche rescue gear (beacon, probe, shovel) and participating in avalanche education—and why some riders are not. The survey is confidential and anonymous. Your feedback is invaluable in improving avalanche education and awareness. Please take a moment to share your experience and help us make a difference:

https://eoustmhs.qualtrics.com/jfe/form/SV_3L8QKAuZzcxJBLo

 

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