Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 6 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

The likelihood of triggering a large avalanche has increased due to recent snow and rain. Smaller, less consequential slides involving new snow could step down to a buried weak layer, causing a destructive avalanche. Make conservative decisions and stick to lower-angle slopes far from the runouts of larger terrain.

Lawinenprobleme

  • Storm Slabs

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

    Fresh snow from yesterday (Wednesday) will be sensitive to the weight of a human on skis or a machine. Avalanches will occur on common terrain features, such as steep breakovers or directly below a ridgeline. A relatively small avalanche involving recent snow could trigger a deeper buried weak layer. The resulting avalanche will be large and likely break much wider than you expect. 

    Give the recent snow time to strengthen with the layer beneath it. If you choose to ride in terrain where the Persistent Slab problem is less likely to exist (SW and W slopes), stick to concave, supported slopes. Small slopes with terrain traps below you will exacerbate the problem. Think about the consequences of being involved with moving snow before committing to a slope. Choose slopes with clean runouts.

    (12/10/2025)

    Expect storm slabs today to be similar to the one photographed here. Slabs may be thicker in wind-drifted areas. 

    Photo: Flathead Avalanche Center

  • Persistent Slabs

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

    Yesterday’s (Wednesday) wet storm loaded an already precarious snowpack. The additional weight of the recent snow and rain increases the likelihood of triggering a large avalanche on slopes that face NW-NE-S. Slabs will fail on a weak layer buried 1 to 4 feet deep. Surviving being caught in a slide like this will rely on luck. 

    Don’t base the outcome on a gamble. Stick to lower-angled slopes and keep your route of travel away from the runouts of steep terrain above you. Slides will entrain a large volume of snow, potentially reaching the toe of large avalanche paths.

    (2/16/2026)

    The crown of a large (D2) avalanche. This avalanche failed on a ENE aspect at 6250 feet. 

    Photo: Cam Johnson

Avalanche Discussion

As Rob’s video from yesterday highlighted, the sensitivity of the buried weak layers has trended down. Snowpit test results from a month ago showed propagation with easy force in many locations. As we look at this week, we are finding that hard force is necessary to achieve propagating results. 

Signs of a stabilizing snowpack have some nuances, though. A month ago, the weak layer was 6 to 8 inches beneath the surface, and it was easy to trigger avalanches. A relatively thin slab sliding on a slick crust was fascinating and exciting to watch, yet mostly benign to travel through. Weak layers are now buried 1 to 4 feet and deeper in wind-loaded areas. Currently, the consequences of being caught in a hard slab avalanche have significantly increased. 

With the loading received yesterday and continued precipitation throughout the week, we can expect the sensitivity to remain somewhat constant or slightly increased. We will start to see clues such as whumphing, collapsing, or even remotely triggering avalanches diminish. However, the structure remains present for large, very consequential avalanches.

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