Lawinenlagebericht

Swan Range

Flathead Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

It is possible to trigger a destructive avalanche that fails deep in the snowpack. Recent snow and wind-drifted snow formed sensitive new slabs that may be easy to trigger. Avoid both avalanche problems by sticking to low-angle terrain.

An Avalanche Watch has been issued. Very dangerous avalanche conditions will develop overnight and tomorrow. Expect widespread areas of unstable snow. Large avalanches will fail naturally.

Lawinenprobleme

  • Persistent Slabs

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

    Large, destructive avalanches have occurred naturally in the last 3 days. The most likely place to trigger one of these beasts is at upper elevations and on slopes that face NW-NE-S. Trigger points are where the weak layer is buried closer to the surface. Unfortunately, most of the time, it is impossible to identify those locations. Rocky outcroppings or wind-swept surfaces may give you clues about where those shallow areas are.

    You are unlikely to notice obvious signs of instability, like collapsing or cracking, before triggering a slide. Snowpit tests may yield variable results, so rely on snowpack structure and recent avalanches when making decisions.

    Your simplest and safest option is to avoid the problem by selecting low-angle slopes that are not connected to steep terrain. You are also less likely to trigger an avalanche on one of these weak layers where a hard and supportable crust exists just beneath the recent snow.

    Overnight, the likelihood of natural avalanches will increase. Expect very large avalanches to fail naturally on these weak layers. Slides may run into lower elevations.

    (3/8/2026)

    A large natural slab avalanche on the slopes below the Little Matterhorn in the Avalanche Lake basin. This avalanche likely occurred when a smaller avalanche stepped down to a weak layer. The blue arrows indicate the crown of the thinner slab avalanche. Wind-drifted snow will continue to overload buried weak layers. Natural and human-triggered avalanches are possible on this layer. 

    Photo: Max Millington

  • Wind Slabs

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

    Yesterday's (Tuesday's) storm overproduced. The Swan Range picked up 2 to 8 inches of new snow, and the Whitefish Range picked up 1 to 4 inches. Convective snow showers led to localized bands of precipitation. Snow totals were variable within the forecast zones. Moderate southwest winds drifted this snow into fresh slabs.

    If you are traveling in an area favored by recent snow, expect to find slabs of drifted snow downwind of saddles, ridges, and cross-loaded gullies. In sheltered areas, you may encounter a loose dry avalanche problem or a thin storm slab problem. These may be sensitive to a rider's weight due to an underlying crust. Cracking around your board or machine indicates you found a slab. Wind-textured surfaces or dune-shaped drifts are visual clues that this problem exists. Seek out terrain sheltered from southwest winds.

    (3/10/2026)

    You may encounter unstable slabs of snow on wind-affected slopes, or in sheltered areas favored by recent snowfall.

    Photo: Flathead Avalanche Center

Avalanche Discussion

We have issued an Avalanche Watch. Very dangerous avalanche conditions may develop overnight and tomorrow. The avalanche danger will spike with new snow and gale-force winds. Very large avalanches will fail naturally. Plan an early exit today and avoid being out overnight.

The recent warm and wet weather left us with another hard and supportable crust beneath yesterday’s storm snow. Riders are finding this hard crust to at least 6600 feet. You can easily boot around on it, and it also supports a machine sidehilling. This has changed the snowpack structure in areas where it exists.

For the rider, it is less likely to trigger an avalanche on a deeply buried weak layer when a hard, supportable crust exists above. Remember, unlikely and impossible are not the same. Our team is still traveling conservatively at middle and upper elevations. As for natural avalanches, this crust may play a vital role in their size and timing in the coming days. Crusts often allow the snowpack to withstand more weight before catastrophically failing. So, this hard crust may delay the initial onset of avalanches deep in the snowpack, but when they start failing, they will likely go BIG. Currently, we don’t know how high this crust extends.

If the next few days play out as forecast, we expect an impressive natural avalanche event. Almost all of our recent natural avalanches have been large enough to snap mature trees. We expect more of the same as snow piles up. The travel advice for the remainder of the week and weekend is as straightforward as it gets: Avoid all avalanche terrain. Be safe out there.

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