Lawinenlagebericht

Bitterroot

West Central Montana Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
1 · Gering
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Kernpunkte

Human triggered avalanches are likely, and large natural avalanches remain possible. An overnight refreeze has dampened avalanche activity for the morning. Below the crust, the snow remains wet and once the crust breaks down, avalanche activity will resume rapidly. 

Avalanche danger is trending down, but the consequences of being caught in a large wet slab are potentially unsurvivable. When in doubt, give yourself a wide margin of safety and  keep it simple by managing the problem through terrain selection. 

Lawinenprobleme

  • Wet Slabs

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

    Natural wet slabs are possible today on all aspects, and human triggered avalanches are likely on slopes where you find yourself sinking into wet or unsupportable snow. 

    An overnight refreeze will help dampen avalanche activity today as it will take time for the surface crust to break down before more meltwater is added to the snowpack. The key point is that even with a crust at the surface, the snow will remain wet underneath. Moisture is still moving through the snowpack and pooling around weak layers like crusts and buried facets. 

    As these layers lose strength, large wet slab avalanches are possible. 

    Wet slabs are difficult to forecast exact timing. Small changes across a zone like cloud cover, wind speed, or just a few degrees of slope angle changing the amount of incoming sun can make slopes avalanche naturally or not.  Over the past week, we have seen a significant natural avalanche cycle, especially around Lost Trail Pass where tree snapping large avalanches ran beyond their normal tracks. 

    Large cornices are failing with the heat and triggering avalanches below. Don’t linger under cornice today! 

    There is no good snowpit test for assessing wet slab potential. A lack of results in pit tests doesn't mean avalanches are unlikely. Look for wet saturated snow. If you find it,  avoid slopes over 30 degrees. 

    Other wet snow problems you may encounter today:

    • Wet Loose: Expect wet loose avalanches on solar aspects today. It will take time for the surface crust to break down and begin the wet loose activity for the day. Keep in mind with wet snow underneath the crust, once the crust breaks down avalanche activity will start rapidly. The size of all wet loose avalanches will be dictated by the size of the slope and amount of snow available for the avalanche to entrain on its way down. 
    • Glide: New glide cracks are opening in the Bitterroot, and we’ve seen evidence of recent glide avalanches. Glide avalanches are incredibly difficult to predict. The time between when a crack opens and when an avalanche occurs can be measured in minutes or weeks. A common trend is glide avalanches failing on days when liquid water is actively moving through the snowpack (like today). 

    (3/17/2026)

    Large glide crack opening up on N-facing slope at 6,000'

    Photo: Ben VandenBos

Avalanche Discussion

Finally some cooler temperatures in the 20s, clear skies overnight, and a skiff of upper elevation snow yesterday. While the surface of the snow may feel cold and frozen this morning, underneath the crust the snowpack remains a wet warm mess. Don’t let your guard down on wet snow problems because you are moving around on frozen snow or crusts.  The SNOTEL sites did not register any new snow yesterday, but if yourself moving through 2-6 inches of new snow, start thinking winter. Be ready for wind slabs to run far and fast on the new snow/crust interface. 

Avalanche danger is decreasing from high after an extended period of elevated danger that produced some monster avalanches. That doesn’t mean the danger has gone away! Our next state of the snowpack will dive deeper into what caused this avalanche cycle, but in summary, weak layers formed in late January and early February that were subsequently buried with snow and preserved. March 12-15th saw some wild snowfall and SWE (snow water equivalent) numbers, pushing these buried weak layers to their breaking point. The central Bitterroot was the focus with mile wide avalanches failing. For the past week, we flipped a switch from winter to June and began packing heat into the snowpack. Melt water percolated down and saturated those January and February layers, removing their strength until they began to fail naturally. In short, it was a wild avalanche cycle that extended avalanche paths by running beyond their previous track. 

Can you get high enough to get above the wet snow? We don’t have any data right now from the tallest peaks of the Bitterroot. Some dry powder may still exist above 8500’ on north aspects. If you do climb up there, be alert for normal winter avalanche problems, especially the potential for dry persistent slab avalanches to fail on the January and February weak layers. These may be layers of buried near surface facets, or pockets of surface hoar in moderately sheltered terrain. 

On the opposite end, most  low elevations do not have enough snow to produce avalanches except for specific areas like lolo pass or isolated north facing low elevation slopes. The primary concern is larger avalanches running through elevation bands into low elevation terrain. 

Don’t trade the skis for golf clubs yet, winter isn’t over.  Let us know what you see by submitting an observation and stay dry today!

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