Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
4 · Gross
Waldgrenze
4 · Gross
Unterhalb
3 · Erheblich
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Kernpunkte

Large, destructive natural avalanches continue to release daily. A gradual drop in air temperature will do little to reduce the deeper hazard today—liquid water moving through the snowpack keeps buried weak layers primed for failure. Stay well back from any steep slope and its runout.

An Avalanche Warning is in effect for the Flathead Range, and the Lake McDonald and Marias Pass areas of Glacier National Park. 

Lawinenprobleme

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–3.5

    Recent slab avalanches have been breaking 4–10 feet deep on the January Drought Layer. Some are failing as dry slabs, while others may be wet—but that distinction matters little right now. Meanwhile, destructive wet loose avalanches have been entraining the deep recent snow from last week. After significant rainfall and nearly five days without a refreeze, liquid water has penetrated deep into the snowpack, weakening an already fragile structure. Cooling at the surface today will not immediately improve those conditions at depth.

    Large, destructive avalanches continue to confirm this pattern. Yesterday, a 5’ thick slab avalanche released on Devils Hump, and another D2.5 wet loose avalanche carried debris far into lower elevations. These are unsurvivable events.

    Wet loose avalanches, wet slabs, and dry slabs are all in the cards today. The only effective way to manage this problem is to stay well away from steep slopes. Even forested areas are not safe—avalanches of this size can snap trees and push debris into low-angle terrain and areas far below the start zone.

    (3/19/2026)

    In at least a few locations, water has pushed deep into the snowpack.  Large avalanches are more likely on slopes where water has reached buried weak layers. 

    Photo: Flathead Avalanche Center

  • Cornices

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–3.5

    Last weekend's snow and wind grew impressive cornices along alpine ridges. Sustained above-freezing temperatures and rain have weakened these overhanging ledges of snow, and failure remains possible. Tumbling chunks of snow can cause large avalanches to fail on buried weak layers. Stay well back from the edge if traveling along ridgelines.

    (3/20/2026)

    Rain and warming have weakened cornice across the region.  Tumbling cornices can often trigger large avalanches on the slopes below. 

     Photo: Adam Clark

Avalanche Discussion

Today’s cooling trend will bring a welcome reprieve from the sustained warm, wet conditions of the past week. While our bodies will notice this change quickly, deeper layers in the snowpack will not. The slab continues to change, and though the spigot will shut off at some point today, the water in the hose still has to make its way through the snowpack. Where it winds up, we don’t yet know.

Water movement through snow is highly variable, even on the same slope. Combine that with differences in prior snowpack structure and a very different weather pattern across the advisory area during this warmup, and you end up with a lot of uncertainty. The Flathead appears to have experienced the most significant rainfall and melt, with Tunnel Snow Station losing a staggering 34” of snow over the past week, while most other stations have lost 9–11”. Rain reached far higher in the Flathead Range—up to roughly 8,000’—whereas in the southern Whitefish and northern Swan, runnels generally stopped around 6,000–6,500’. The Flathead Range remains primed for big avalanches today. 

Even as danger drops from high to considerable in the Swan and Whitefish Ranges today, caution remains critical—large, destructive avalanches are still possible. When the January Drought Layer fails, it fails massively. Yesterday on Lost Johnny, we observed a slide that crossed two faces, breaking over 4,000’ wide and more than 6’ deep at its thickest point. This is the scale of what we’re dealing with.

In many start zones above 6,500’, the JDL remains dry and intact. This layer will continue to guide our travel decisions, likely for the rest of the season.

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