Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired last year. You’re viewing past conditions, not the current bulletin.

Highlights

Fresh snowfall and wind will form drifts of snow sensitive to the weight of a rider. Steer away from areas of wind-affected snow like etched surfaces or dune shaped features. Seek out slopes that are less steep or more sheltered from the wind if you notice blowing snow, or cracking around your feet or machine. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Today's snowfall and moderate to strong west winds will form sensitive drifts on typical leeward slopes at middle and upper elevations. Blowing snow will point in the direction of freshly forming slabs. You are most likely to find these along ridgelines and in open bowls or mid-slope gullies.  

    Soft slabs will give signs of instability by cracking around your feet or machine.  Hard slabs will support your weight and can break well above you or wider than expected. Avoid both by steering away from obviously wind-affected areas like etched snow surfaces or pillowy dunes. Slabs 8+ inches thick can be troublesome for a rider. Recognize that slab thickness can vary dramatically across a slope. Even small slides can be hazardous if they occur in extreme terrain, above a terrain trap, or trigger a larger avalanche on a buried weak layer. 

     

    (3/19/2025)

    Cornice (top left), dune-shaped features (middle) and scalloped snow surfaces (bottom right). Theses are all signs that the wind has been at work.  Expect to find slabs sensitive to the weight of a rider on slopes with these clues.

    Photo: Rob Millspaugh

  • Persistent Slabs

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

    Rocky, wind-affected, alpine slopes facing NW-N-NE-E-SE are where you are most likely to trigger a large avalanche on a buried weak layer. The snowpack on these slopes has variable depth and it is eaiser for a rider to trigger slabs at thin spots, where weak layers are closer to the surface. If you are traveling in this type of terrain, dig below the surface to assess the snowpack structure. Sudden collapses and propagation in tests indicate weak structure. Increase your margin for safety by choosing slopes with planar or concave profiles, deep and consistent snow cover, and minimal overhead hazard. 

    It is possible (but unconfirmed) that large avalanches failed on these layers during last weekend's snowfall and wind-loading. In most cases, layers of surface hoar, facets, and faceted crusts formed in January are buried 3 to 4 feet deep and are unlikely to be affected by a rider.  Larger triggers - like failing cornice or surface slabs - could still trigger large avalanches where weak layers are buried deeply. 

     

    (3/17/2025)

    The crowns and debris of large natural avalanches that look to have failed March 15 or 16. The flanks of the slide in the center are thick enough to suggest the slide released on weak layers buried deep in the snowpack.

Avalanche Discussion

Spring officially started at 3:01 this morning. Cue snowfall. 

Moderate mountain snow showers should become more widespread through the first half of the day. Tunnel Ridge is off to an early lead with 3 to 4 inches in the last 3 hours. Snowfall will transition to convective showers in the afternoon. These cells can produce highly variable accumulations. If you find 8 or more inches of new snow, you can expect to see some instabilities (soft slabs, loose dry sluffing) creeping into wind-sheltered train. Opt for simple, low-angle terrain if you reach this threshold. 

Between snow showers, we could see some breaks of sun this afternoon. With dry snow on the ground, it won’t take long for the strong spring sun to wreak a little havoc. Any resulting wet snow should be more of a menace than a hazard today. Keep an eye out for clues that the snow surface is transitioning to wet: snow shedding from the trees; glopping to your skins, boards, boards or machines; fresh rollerballs and pinwheels. Consider moving to less steep or more shaded slopes if you see these signals.

Check out Telefestivus at Blacktail Ski Area on Saturday, March 22, and Sunday, March 23. In conjunction with the event, Tamarack Brewing will host a fundraiser with a raffle and film for the Friends of the Flathead Avalanche Center from 5 to 8 PM Saturday, March 23. 

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