Bollettino valanghe

Whitefish Range

Flathead Avalanche Center
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Pericolo valanghe

Thu
Alta quota
4 · Forte
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 8 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Very dangerous avalanche conditions will develop throughout the day. Natural and human triggered avalanches will become very likely. Keep travel to simple terrain. Any natural or human triggered avalanche today will likely run far downslope. 

Problemi valanghivi

  • Storm Slabs

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

    Storm totals are expected to be 8 to 16 inches by the end of today (Wednesday). Sustained winds will transport snow into thick slabs on leeward sides of ridges. Snow densities will increase throughout the day leading to an upside down snowpack. Triggering an avalanche 1 to 2 feet thick will become more likely throughout the day. 

    Place yourself in a location far from steep slopes, including the runouts of large paths, especially as the storm totals add up. Convexities on the slope, on any aspect, are the most likely places to trigger an avalanche of this nature.

    (12/9/2025)

    A large slab avalanche on a wind-loaded slope that failed during the recent Atmospheric River event. Debris traveled nearly 3000' to the valley floor. The wind blows from right to left in this image.

    Photo: Mark Dundas

  • Loose Wet

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

    Today, the rain line will rise from 4,000’ this morning, to 7,000’ this evening. Avalanches will fail naturally as slopes of dry snow take on rain. Roadcuts, steep slopes, and underneath cliff bands are likely spots to encounter these.

    Wet Loose problems are relatively easy to avoid by staying out of steep terrain. Even being caught on a short slope, such as a roadcut, could lead to a nasty outcome.

    Rain on snow is a surefire recipe for natural avalanches. If the flakes turn to drops while you’re out today make sure to find gentler terrain and head for home.

    (12/9/2025)

    Multiple Wet Loose slides are visible in the Snyder Lake basin beneath the Little Matterhorn. These failed during the recent Atmospheric River.  

    Photo: Mark Dundas

Avalanche Discussion

Tuesday came in like a lion and left like a lamb. A natural avalanche cycle was well documented in the Flathead/Glacier Park regions, and we received one observation from outside the WMR boundary. Numerous 18 to 24 inch thick natural slab avalanches occurred yesterday morning. I assume this occurred in conjunction with a rising freezing level and early morning rain on snow.

Yesterday (Tuesday) ,temperatures dropped below freezing throughout the day and associated winds tapered off as well, though remained at speeds capable of transporting snow. We were left with partly clear skies and a pause in avalanche activity.

Today, however, we’re right back in the ring. Storm totals are expected to be 6 to 16 inches by the end of the day. As this surge of moistures impacts our mountains it will dump wet snow, potentially followed by more rain on snow. Yesterday showed us the resulting carnage that events such as these can have.

Make plans that are simple today. If the freezing levels don’t rise as high, or we don’t get quite as much snow as predicted, avalanche conditions will remain dangerous. I don’t lack confidence about the “if” there will be avalanches today, it’s more about their size and when they will occur. Either way, enjoy the bountiful fresh snow and be cognizant of the slope angles surrounding you. Bring an extra shell, pair of gloves and pay attention to the precipitation type and temperature you’re experiencing. 

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