Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

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

An Avalanche Warning has been issued. Rain and warm temperatures are creating very dangerous avalanche conditions. Stay off and out from underneath all avalanche terrain. Recent avalanche activity includes a tree snapping 10+ foot hard slab that broke over 3000 feet wide and traveled 2500 vertical feet.

There is uncertainty about the timing of a widespread natural avalanche cycle. It will happen sometime between today and Friday. Regardless, the travel advice right now fits HIGH Avalanche Danger.

Lawinenprobleme

  • Loose Wet

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

    Rain and warm temperatures are wetting the snow surface and causing it to slide. Pinwheels were easy to initiate yesterday. With continued warming  and rain overnight and today, I’d expect to see point releases to start entraining large volumes of snow. Wet loose avalanches will occur on all aspects at lower and middle elevations. I expect them to start climbing into the upper-elevation band as the rain/snow line rises today.

    Rollerballs or pinwheels are signs of an impending wet loose cycle. Rocky and very steep slopes are commonly the first to slide. Human-triggered wet loose avalanches will be easy to trigger today. Wet debris is destructive and difficult to escape. Avoid traveling in steep terrain. 

    (3/17/2026)

    It didn't take much for small natural rollerballs to clump into tire-sized blobs on steep roadcuts. A clear sign of developing wet loose snow avalanche hazard.

    Photo: blase reardon

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–4

    Warming temperatures and recent wind loading are increasing the threat of unsurvivable and very destructive avalanches. The avalanche on Nyack Mountain in the last 24 to 36 hours is clear evidence to stay FAR FAR away from avalanche terrain. Avalanches are reaching sizes that can clear substantial amounts of forest.

    As water moves through the snowpack, slab avalanches will fail as either wet slab avalanches or persistent slab avalanches. Avalanche activity will spike once water reaches the January Drought Layer. Predicting that timing is very challenging. Regardless of whether avalanches fail as wet slabs or persistent slabs, the travel advice is the same. AVOID avalanche terrain.

    (3/17/2026) Photo: Michael Reavis

    This avalanche failed within 24 to 36 hours. It is categorized as a D4. That size avalanche can destroy buildings and snap mature trees like twigs. 

  • Wind Slabs

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

    Plan a foolproof route to upper elevations. When you get there, expect to encounter slabs of wind-drifted snow. Wind slabs may be 1 to 3 feet thick and hard thanks to recent strong southwest winds. Triggering a small wind slab can step down to an unsurvivable avalanche. We assume this was the case in the recent Nyack slide.

    Avoid dune-shaped drifts and pillowy-looking surfaces. Cracking around your board or machine is a sign you have found a slab. 

    (3/17/2026)

    Windslab activity at ridgeline that resulted in a larger, very destructive slab avalanche that failed on buried persistent weak layers. 

    Photo: Michael Reavis

Avalanche Discussion

We’ve issued an Avalanche Warning for the next 24 hours. This Warning will likely continue through Friday. Rain on snow and warming temperatures today should create a widespread wet loose avalanche cycle. I’d expect to see some smaller avalanches trigger a few very large and destructive avalanches failing deep in the snowpack.

Whether we see a widespread avalanche cycle today or not, the travel advice is simple - very dangerous avalanche conditions exist, and we don’t recommend traveling near avalanche terrain. Based on the destructive size of the recent avalanche on Nyack Mountain, we don’t recommend traveling into any valley bottom in the Flathead Range. In other ranges, steer far away from the runouts of avalanche paths as well. Avalanches that size can clear mature stands of timber.

The eastern half of the forecast region is warm with temperatures in the mid-30s and low 40s as of 5 AM this morning. Flattop in central Glacier National Park has picked up an inch of precipitation with temps in the upper 30s and low 40s. That is a lot of rain. Meanwhile, Whitefish Mountain Resort's summit station has received 1 inch of snow. Our 7000-foot stations are near-freezing, while our 6000-foot stations are in the mid-30s. Rising freezing levels will push rain into the upper-elevation band across all forecast zones today.

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