Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Thu
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Prolonged warm temperatures and sunshine make it likely for you to trigger a wet snow avalanche on steep slopes.  Meltwater in the snowpack can cause very large and destructive avalanches to fail on buried weak layers or even at the ground. Choose low-angle slopes that are not exposed to overhead hazards like avalanche paths or overhanging cornice. 

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–3

    The surface snow on most steep slopes is wet from sustained warm temperatures and rain. Today's slightly warmer temperatures and intense spring sunshine will keep the meltwater flowing. Water percolating through the snowpack can destabilize weak layers and cause wet slab avalanches that break at various depths. Avoid traveling on or under steep slopes especially during the heat of the day. 

    Wet loose avalanches are likely where dry snow is transitioning to wet for the first time. This change is evident when rollerballs start fanning down a slope from trees, rocks, or your skis, board, or snowmachine. Move off and out from under steep slopes when and where these conditions exist. 

    Rollerballs and debris from surface slides can trigger larger slab avalanches.

    (2/1/2024)

    Wet avalanches may occur as sluffs or slabs today.  

    Photo: Mark Dundas

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3.5

    On Monday, very large avalanches broke on weak layers buried deep in the snowpack, or even near the ground.  At least a few of these were caused by large triggers like wet loose debris or cornice fall. Continue to avoid the runouts of steep, upper-elevation start zones. Especially those that have unsupported, convex profiles; have snow cover that varies in depth due to wind scouring and drifting; or have large overhanging cornice looming above them. 

    Shaded upper-elevation slopes are also where you are most likely to find lingering slabs of dry snow. These may become reactive during today's warming temperatures and have the potential to step down to buried weak layers. 

    (3/24/2025)

    Recent hard slab avalanches have failed on buried weak layers or even near the ground. Most activity has been on unsupported, rocky alpine terrain like this slope in the Skyland region. 

    Photo: Michael Reavis

  • Glide Cracks

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Warming temperatures may increase the likelihood of large and destructive glide avalanches. Some glide cracks may have been covered by snowfall over the last two weeks. In the Swan Region, at least 38 were visible earlier this month between Hash Mountain and Wolf Creek (previous observation). 

    Glide avalanches are notoriously difficult to predict.  Don't push your luck as these avalanches will involve the entire season's snowpack. Avoid this problem by steering clear of slopes where glide cracks are present.

    (1/19/2025)

    A yawning crack on a southerly slope in the southern Whitefish Range. Do not dawdle below glide cracks, especially during periods of warm temperatures.

    Photo: Flathead Avalanche Center

Avalanche Discussion

We built up an impressive snowpack during the second half of March. Now we’re putting it through the gauntlet. Stage One was 1 to 2 feet of snowfall late last week. Stage Two was warming temperatures and rain up to 7,000 ft and maybe higher. Although observations have been limited, it appears each of these tests produced widespread cycles of large to very large avalanches (Skyland, JFS, Condon).

On to Stage Three! Warm temperatures will persist today without an overnight refreeze. Intense spring sunshine could boost meltwater production and increase avalanche activity through the day. The forecast calls for some high-level clouds to develop later today and light southwest winds. Increasing cloud cover could limit the impact of today's sunshine on solar aspect, but could also increase warming on shaded slopes due to greenhousing.

The avalanche danger is rated High for upper-elevations in the Flathead Range and Glacier National Park. This zone has more terrain above the (presumed) rain/snow line. These slopes might have snuck past the rigors of Stage Two and will be more vulnerable today's warming and sunshine.  Expect natural avalanche activity and elevated danger anywhere you encounter dry snow that is transitioning to wet for the first time. 

Several factors are contributing to high uncertainty today:

  1. We have limited observations especially from upper-elevations.
  2. Liquid water moving through the snowpack can cause avalanches to fail in surprising ways. 
  3. Forecasting cloud cover can be fickle and today’s clouds could have a big impact on natural avalanche activity.

When uncertainty is high, it is best to make conservative and adaptable travel plans. 

Regions covered