Lawinenlagebericht

Bitterroot

West Central Montana Avalanche Center
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Lawinengefahr

Sun
Hochgebirge
2 · Mässig
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Kernpunkte

Small human triggered avalanches are likely in fresh wind drifted snow at upper elevations today. Red flags like cracking, collapsing, and recent avalanches are signs to avoid avalanche terrain. Although unlikely, you could also trigger deeper avalanches that fail on buried weak layers around crusts. 

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–1.5

    Yesterday, moderate west winds drifted 2 to 5 inches of new snow into small fresh wind slabs at upper elevations. Observers found sensitive fresh wind slabs near ridgelines and just below cornices. Today, human triggered avalanches are likely anywhere the wind has drifted the new snow into slabs 6 inches thick or more. 

    Identify wind slabs by looking for stiffer pillow-shaped deposits and wind drifts. Wind slabs are most likely today on northeast, east, and southeast aspects. Avoid slopes over 30 degrees if you see signs of instability like recent avalanches, cracking, or collapsing. Remember, even a small avalanche can have serious consequences. 

    (1/2/2026)

    Small fresh skier triggered wind slab on an upper elevation east aspect

    Photo: Arden Feldman

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    Although unlikely, you could still trigger a large persistent slab avalanche that breaks 2 to 4 feet deep. This is a classic low-likelihood high-consequence avalanche problem. Our main concern is a weak layer of sugary facets surrounding a crust that formed in mid-December. We have not seen recent avalanches on this layer, but it has been reactive in snowpack tests. If you’re unlucky, you could find the right trigger spot. 

    You are unlikely to see obvious signs of instability, like cracking or collapsing, before triggering a persistent slab avalanche. Dig down and look for weak snow surrounding crusts. If you find strong snow over weak snow, stay off slopes over 30 degrees. 

    The highest elevation north-facing slopes have additional weak snow near the ground. This snow is gaining strength, but could be triggered in isolated areas by a very large load.

    (12/31/2025)

    Snowpit on a northeast aspect at 7650 ft in the Bitterroot

    Photo: Arden Feldman

Avalanche Discussion

Wind speeds were very effective for building fresh wind slabs yesterday. In the Rattlesnake, observers found fresh wind slabs that were 6 to 18 inches deep with only 2 to 3 inches of new snow. The avalanches were relatively small and confined to near ridge tops, but still impressive considering how little snow fell. In areas without wind loading, you are much less likely to find enough new snow to trigger a fresh slab avalanche. However, if you do find a location up high with more than around 6 inches of new snow, look out for larger wind slabs and avalanches in wind protected areas as well. Avalanches in the new and wind drifted snow could be extra sensitive because they lie on weak snow surfaces that formed earlier this week. 

Unfortunately, rain fell up to at least 6000 ft yesterday, and the snow surfaces at lower and middle elevations got wet. Today, temperatures will remain warm, and the sun could shine in the morning. If you find yourself sinking into wet or unsupportable snow, or seeing roller balls start to entrain mass, it’s time to get out of avalanche terrain. 

Keep in mind that the persistent slab problem still lingers. Each new storm increases the weight of snow over existing weak layers and changes the structure of the overlying slab. Eventually, the increased load can lead to a period of persistent avalanche activity. Sometimes a series of small incremental loads can tip the balance. 

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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