Avalanche forecast

Bitterroot

West Central Montana Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 8 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

Large and destructive human triggered avalanches are possible in areas with buried weak layers. Fresh wind slabs will grow this afternoon and tonight as a storm brings snow and strong winds. Stick to low angle slopes if you see red flags like recent avalanches, shooting cracks, or collapsing. You may not see signs of instability before triggering a deeper avalanche on a buried weak layer. 

The avalanche danger will likely rise to CONSIDERABLE overnight. If the storm arrives early, dangerous conditions could develop by the late afternoon. 

Avalanche problems

  • Persistent Slabs

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

    It remains possible to trigger a large persistent slab avalanche that fails on weak layers buried 2-4 feet deep. These weak layers include crust facet interfaces and facets near the ground. The crust facet layer is the most widespread and concerning. This layer is buried 2-3 feet deep and produces full propagation in snowpit tests. It can be a tricky persistent weak layer to manage and highly elevation dependent. Triggering a large and destructive persistent slab avalanche on weak snow near the ground is also still possible on high-elevation northerly slopes. These are locations where early-season weak layers were buried, and were not saturated by rain earlier in December. This setup only exists in isolated locations, but the consequences will be high if you trigger one of these avalanches. 

    Whumfing and collapsing are signs of unstable snow, but you may not see any signs of instability before triggering an avalanche on these layers.  Dig in the snow and look for poor snowpack structure with a slab above a weak, sugary layer. Manage the problem with slope angle and stick to slopes less than 30 degrees. Keep in mind that persistent slabs could also be triggered remotely, from low angle slopes above, below, or to the side of steeper slopes. Tonight’s snowfall could add enough load to the weak layers to make persistent slabs more sensitive. 

    (12/24/2025)

    Snowpit on a northeast aspect at 7200 ft

    Photo: Arden Feldman

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Fresh wind slabs will grow today and tonight as a cold front brings snow and strong southwest winds to the region. We can expect 2 to 5 inches of snowfall during the day today, and total accumulations of 6 to 12+ inches by tomorrow morning. 

    This morning, before the snow and wind ramp up in the afternoon, you could still find lingering older wind slabs formed by recent shifting winds. By the late afternoon, small fresh wind slabs will become likely. They will grow large enough to bury you tonight, and could fail naturally. If the storm arrives early, expect larger wind slabs by the late afternoon. 

    Wind slabs can be identified by their smooth or pillow like appearance. They often form just below ridgelines, in gullies, and below convex rollovers. However, today’s winds will be strong enough to build wind slabs in unusual locations, lower down on slopes. If you find more than 6 inches of wind drifted snow, expect to find fresh wind slabs. If you see signs of instability like recent avalanches or cracking around your skis or sled, stick to low angle slopes less than 30 degrees. Consider that a smaller wind slab could step down and trigger a larger persistent slab. 

    (12/24/2025)

    A small intentionally triggered wind slab on an upper elevation northeast aspect

    Photo: Arden Feldman

Avalanche Discussion

A strong cold front will impact the region this afternoon through tomorrow morning. We can expect 6 to 12+ inches of new snow in the mountains. Strong southwest winds will drift the snow into fresh wind slabs. The avalanche danger will begin to rise this afternoon and likely reach Considerable sometime tonight. There is uncertainty in the exact timing of the storm and significant snowfall. If the storm arrives early, the avalanche danger could reach Considerable by the late afternoon. Stay alert for changing conditions. Keep track of the snow accumulations today, and when you start finding fresh drifts deeper than about 6 inches, expect to find fresh wind slabs. 

On Christmas Eve, a warm storm brought light rain up to at least 7000 feet across the region. Cooler temperatures arrived last night, and the snowpack began to refreeze. Expect variable riding conditions if you head out in the backcountry this morning. 

The WCMAC team is excited to be back to issuing full avalanche forecasts. Avalanche forecasts will be issued on Thursdays, Fridays, Saturdays, and Sundays. A general information product will be issued on Mondays to cover the Monday-Wednesday period. We hope to begin forecasting for the Seeley Lake zone next week. Thank you for your patience while we worked through our agreement with the Forest Service! 

Let us know what you see by submitting an observation. We appreciate all observations, no matter how small, as our forecast area is large, and it helps us understand conditions across all zones. 

Ski and ride safe. 

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