Bollettino valanghe

Swan Range

Flathead Avalanche Center
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Pericolo valanghe

Wed
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 6 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Very dangerous avalanche conditions exist. Human-triggered avalanches are very likely, and as you gain elevation, the chances for natural avalanches increase. Triggered and natural avalanches will involve dangerous amounts of debris. Stay far away from any steep slope. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Very Likely
    Dimensione
    2–3

    Large, remotely-triggered avalanches have become commonplace over the last week. Do not let yourself become desensitized to the important feedback. Recent wind and fresh snow have thickened the slab above these buried weak layers and strained them more. Expect that slopes will be more sensitive to the weight of a skier/rider than before yesterday’s (Monday) loading event. This will be especially prevalent on leeward slopes that have been affected by the wind.

    Slabs may break 2 to 4 feet thick, run fast, and break much wider than anticipated, connecting multiple start zones and releasing destructive amounts of debris. We have seen crowns reported to be well over a thousand feet wide. Make sure that the terrain you are in puts you well back from where any triggered avalanche could reach. This distance may be much further than you expect.

    Travel advice: Stay well back from the breakover at the top of a slope if traveling on a ridgeline. Stay well back from the runout of avalanche paths if traveling in the valley bottom. The best places to enjoy a respite from avalanche hazards are groomed trails or roads that meander around avalanche runouts in the valley bottoms. 

    (2/21/2026)

    Looking down the crown of a very large (D3) avalanche that took out the entire bowl. This avalanche failed on a layer of surface hoar above a crust that formed during the January drought. The avalanche failed on a north aspect at 7000 feet in the southern Whitefish Range. The avalanche propagated 1500 feet wide and was triggered from a 100 yards away. 

    The orange arrow marks the extent of one side of the crown. In the other direction, the crown continued for many hundreds of feet.

    Photo: Josh Lipkowitz

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2

    New snow and moderate but gusty southwesterly winds have formed fresh slabs on leeward slopes. These slabs should grow throughout the day as the winds continue and more snow falls. Small slabs of drifted snow could step down to deeply buried weak layers, releasing much larger avalanches. These would likely be unsurvivable.

    Stay far back from ridgelines or open saddles. Cracking underfoot is a clue that you have found an unstable windslab. Retreat to an area protected from the wind and lower in slope angle. 

    Recent and drifted snow has buried weak layers. Triggered, fresh wind slabs may step down into deeper instabilities, resulting in very large, unsurvivable avalanches.

    Photo: Chris Craft

Avalanche Discussion

It has been 25 days since Josh and Lydia first documented a remotely triggered avalanche on a buried weak layer in Noisy Basin. Since then, there has been a rash of reports, nearly every day, of skiers and snowmobilers triggering avalanches, being caught and carried, and fully or partially buried. Fortunately, no one has been seriously injured or worse.

Initially, the danger seemed concentrated to the Swan Range. Yet as time progressed, we saw the Flathead/Glacier National Park areas become hazardous, and then Stryker Ridge and the Northern Whitefish Range. While the southern Whitefish Range and areas around the ski resort initially appeared insulated from the trouble, they, too, eventually became more dangerous as observers reported many avalanches and reactive snowpit tests in the last week.

We have elevated the danger to HIGH due to new snow coupled with moderate to strong winds. The Flathead Range received the most snow from yesterday’s (Monday) storm, allowing for greater confidence in middle elevations being more hazardous than those in the Swan and Whitefish Ranges. Southwesterly winds are loading the shaded/leeward slopes that have been producing terrifying avalanche conditions. Without observations from yesterday, it is a bet I’m willing to take that conditions have only become more touchy with this most recent loading. Add more snow today and this evening, and the danger will likely remain across the high country. 

Any steep (greater than 25 to 30 degrees) slope that is shaded and leeward to the wind is likely to slide right now. Skiers outside the Whitefish Mountain Resort boundary observed buried surface hoar on southerly slopes. More wind loading and additional weight from new snow could possibly add another aspect to the already complicated environment. Couple this information together, and the places one can go to avoid triggering or being caught in an avalanche are limited. 

Continue very safe and intentional travel in the mountains. As uncomfortable as it is to submit an observation of a triggered avalanche or an incident involving someone being caught and/or carried, that information helps us pattern the snowpack and keep the community, as a whole, safe.

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