Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Today's avalanche hazards are most widespread on upper elevation, shaded slopes. In this terrain, you can trigger large avalanches involving recently drifted snow on leeward and cross-loaded slopes. The potential for large avalanches that break deeper in the snowpack also exists. After Monday's sun, the best and lowest risk riding today will be on sheltered slopes at mid-elevations. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    Monday night’s winds continued to sculpt fresh wind slabs and stack up cornices from the weekend’s storm snow. Terrain features like ridgelines and rock outcroppings, leeward slopes, and cross-loaded gullies will have this problem. Areas that received the most snow and wind have the highest danger.

    Blowing snow, overhanging cornices, and etched surfaces point in the direction of loading. Wind slabs appear as smooth, rounded surfaces that sometimes have a hollow sound when traversed. We received multiple observations from Monday showing large slides in steep, leeward slopes with possible cornice triggers. Continue to give fresh cornices plenty of space, as they can break back farther than expected. 

  • Persistent Slabs

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

    On isolated slopes, avalanches that break on deeply buried weak layers remain possible. Thoughtful terrain choices can minimize your exposure to this unlikely but serious hazard. So can adjusting to changing conditions; move out from under steep start zones with active wind loading or getting direct sun.

    This hazard is probably confined to slopes where wind-scouring keeps slabs thinner and the weak layers are closer to the surface and slower to sinter. And it probably takes larger triggers to collapse these layers - falling cornices or the debris from avalanches involving surface snow. Nonetheless, it's a hazard worth factoring into  your objectives and travel.

    Choose terrain that has planar or concave profiles, deep and consistent snow cover, and minimal overhead hazards. Lots of terrain meets these conditions, and lots of that terrain has great snow right now. If you do choose terrain where this hazard is more likely, dig to see if the structure is present; sudden collapses and propagation in tests indicate that structure indeed exists.

    (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

Slabs of drifted snow that formed this weekend likely remain sensitive to a person's weight on top-loaded and cross-loaded, upper elevation slopes. However, these slabs look wide and thick and nothing to mess with; see the images from recent obs here and here. Avoiding the start zones where these are likely is the most straightforward way of minimizing the threat these pose. I'd avoid dawdling in the paths of potential slides when there's snow blowing at ridges, or direct sun on cornices or the start zones. On sheltered slopes, the weekend's snow has settled and there's not much evidence it's sensitive to the weight of a rider or rider and snowmachine. 

Lurking 2 to 3 feet below the snow surface are weak layers that developed in January. These strengthened and consolidated in February, and  boy howdy, would I like to write them off as dormant. Then someone sends an image of a large natural avalanche with a crown and flanks that look way too deep for slabs that involve only recent snow. So I just can't ignore them just yet. 

We received several reports noting that Monday's sun was having a strong effect on the surface snow on southerly slopes. After last night's cold temperatures, the wet snow has refrozen, and it will likely remain so under today's cloud cover and cool temperatures. Expect the wet snow to be more of a hazard tomorrow, when skies partly clear. 

Loose dry snow avalanches are becoming less likely as the weekend's storm snow settles. The exceptions might be very steep terrain where the surface snow is not affected by the wind, particularly confined chutes.

Curious about recent developments in tele boots and bindings? Check out Telefestivus at Blacktail Ski Area on Saturday, March 22, and Sunday, March 23. In conjunction with the mind-freeing 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. 

Regions covered