Avalanche forecast

Flathead Range & Glacier NP

Flathead Avalanche Center
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Avalanche danger

Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Out of date — this forecast expired last year. You’re viewing past conditions, not the current bulletin.

Highlights

Conditons are complex, changing rapidly, and dangerous. You can trigger slabs of new and drifted snow and long-running sluffs of loose snow. These sluffs may involve wet snow at low and mid elevations. Natural avalanches are possible; avoid the runouts of steep start zones. 

Update 1315: We have issued an Avalanche Watch for the 24 hours extending from 1300 Sunday to 1300 Monday. 

Avalanche problems

  • Wind Slabs

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

    Today's conditions don't fit neatly into avalanche problem descriptions, so consider this a catch-all for slab avalanche hazards involving new and drifted snow. At upper elevations, expect to find fresh slabs of drifted and wind-stiffened snow on leeward and cross-loaded slopes. Slabs will continue to grow and remain sensitive to a rider's weight on steep slopes through the day. They may release naturally. Thanks to lots of loose snow in the tracks below start zones, debris from these slabs will run far, reaching mid-elevation runouts in larger paths. 

    At mid-elevations, the hazard of triggering slab avalanches will increase through the day as higher-density snow falls on Saturday's loose, low-density snow. Slope angle will make a big difference in how sensitive these slabs are to a rider. You're most likely to trigger them on convex slopes. Shooting cracks are a dead giveaway that slabs are resting uneasily on the snow below them. Step back to lower-angled terrain if you see these. Inconsequential test slopes and hand pits are quick ways to monitor this hazard as it develops. 

    Cracking like this is a clear sign that cohesive slabs are sitting on lower-density, weaker snow. If these extend more than a sled- or ski-length, step back to  lower angled slopes.

    Photo: Flathead Avalanche Center

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Natural and triggered loose snow avalanches are likely today on very steep slopes where the recent snow remains cohesionless. These will involve cohesionless dry snow to start the day; the hazard will be greatest on and below continuously steep slopes where debris can run long distances and gather more snow as it does. They can be a hazard on all aspects at upper elevations, and the steeper the slope, the more likely the snow is to release. Avoid being in or under chutes and other confined terrain, where it can be difficult to escape even small sluffs.

    As the day progresses, more snow falls, and temperatures rise, this hazard will grow at low and mid-elevations. Snow falling from trees and rocks may trigger these naturally. The snow involved will become denser and wetter, and the hazard will spike with any rain. Beware of narrow, steep-sided gullies and drainages, where small amounts of debris can lead to deep burials. 

    (3/22/2025)

    Natural dry loose avalanches in steep, upper elevation terrain. As temperatures rise today, these will become likely and involve wet snow at low and mid elevations.

    Photo: Michael Reavis

  • Persistent Slabs

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

    If anything is going to wake up weak layers that developed in January, it's the large loads of new snow that have accumulated in the past week. The slopes where this is most likely are high, cold, and have variable snow depths.  Today, avoid being under slopes with these characteristics. That might involve some careful map reading, since clouds will obscure terrain above you today. Debris from falling cornices, natural slabs of drifted snow, and sluffs could release these beasts. With lots of snow in the tracks to entrain, they'll run far - even into low elevations in the Flathead Range. Minimize your time in the runouts of large avalanche paths.

    The kind of terrain where the PS problem is still lurking: convex, variable snow depths, steep.

    Photo: Mark Dundas

Avalanche Discussion

Conditions are complex and dangerous this morning, and will only get more so as the day progresses. To boil it down as best I can, the danger posed by large slab and loose snow avalanches will increase with more wind, more snow, and rising temperatures today. The danger will peak late tonight or tomorrow as the snow transitions to rain overnight.

Slabs may consist of drifted snow, wind-stiffened storm snow, or upside-down new snow. Both will become larger and more likely as snow accumulates, though elevation will play a big role in what kind of snow forms slabs. The higher you go, the more wind-blown and stiffened snow will be a hazard. 

As Saturday's mostly cohesionless snow settles, loose dry avalanches are becoming less sensitive to a rider's weight, and it'll take ever steeper slopes for these to release. However, rising temperatures will wet the snow surface, and loose snow slides will become ever more likely - and involve more debris - as this process occurs. And even brief rain showers will spike this hazard.

Whew. Got all that? Keep it simple today - pick routes with minimal overhead hazard and easy escapes back to your vehicle or the ski area. Stick to lower angled slopes, avoid creek beds and gullies, and step back to non-avalanche terrain if you see shooting cracks or recent avalanches. 

Regions covered