Bollettino valanghe

Bitterroot

West Central Montana 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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In sintesi

Dangerous avalanche conditions exist, particularly in upper elevation terrain where the wind is at work. Today's strong westerly winds are making quick work of the new snow, building wind slabs that will be reactive to your weight and may fail naturally. Underneath the recent snow, several concerning weak layers are buried. These have produced natural and human-triggered slides in the last week, and will be more reactive today thanks to the additional load. These types of avalanches may be triggered from long distances below, to the side of, and above steep slopes. Avalanches failing within the new snow can be effective triggers for much larger avalanches that fail on buried weak layers. 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1.5–3

    Multiple weak layers are buried in the upper 1-2 feet of the snowpack. These layers produced human-triggered and natural avalanches prior to the storm that impacted our region since Monday. Remote weather stations tallied 10-12 inches of snow (1 inch of snow water equivalent) since Monday night. Layers of surface hoar are at their worst in shaded middle and upper elevation terrain, with crust+facet combinations found at this interface on sunnier slopes.

    Avalanches that fail on these layers of weak snow will break widely and will be able to wrap around terrain features. This produces large, unpredictable avalanches with deep piles of debris. Importantly, you will be able to trigger these slides remotely — from a distance away from the slope that avalanches. This means that you can trigger slides that fail on steep slopes above you, and run down into flat terrain below. Completely avoiding this problem includes avoiding terrain threatened from above. 

    (2/19/2026)

    Buried surface hoar under 10 inches of recent snow.

     

  • Wind Slabs

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

    With a foot of new snow here in the past 36 hours, you'll want to be on the lookout for a variety of avalanche types involving the recent snow. Your biggest new snow concern will be wind slabs. Look for active snow transport and fresh cornice growth as indicators of wind-thickened slabs on the slopes below. Winds have been pinned out of the west, so these wind features will be most widespread in terrain on the east side of the compass, but may exist on other slopes as well. In steep terrain, you can expect to see sluffing within the new snow, with loose snow avalanches becoming increasingly likely as the day warms and the sun goes to work wetting the snow surface. 

    These "smaller" avalanches will be plenty large to ruin your day or worse, and will be effective triggers for the larger persistent slab avalanches described above as they run downslope. 

Avalanche Discussion

Yesterday's storm fizzled a bit in this forecast zone. We expected to see 20-30 inches of snow (2.5 inches of SWE) piling up, but remote weather stations picked up closer to 10-18 inches (1.5 inches of SWE) at middle elevations. You'll find more snow as you climb higher into upper elevation terrain.

Over the last two weeks, smaller storms have built a slab on top of weak layers formed in January and February. These weak layers produced rounds of natural and human-triggered avalanches in a spotty distribution. The main ingredient lacking in the avalanche equation has been a strong slab over the weak snow underneath. Yesterday's storm added to this building slab, but it wasn't as drastic a change as expected, thanks to the underproducing storm. We are still worried about these layers today, and they should remain at the front of your mind in your travels. Avalanches that fail on these layers will be triggerable from long distances away from steeper slopes. If you are going to ride and play in low-angle terrain today, take the time to make sure that you aren't exposed to avalanches releasing on steeper slopes above you. You can trigger today's avalanches from flat terrain below steep slopes. 

While we may have received the short-end of the snow stick, it looks like we will get a serious helping of wind in upper elevation terrain today. Expect to see lots of snow in the air and plenty of new wind slab growth. These slabs will be smaller than the persistent slabs described above, but could easily take you for a ride. Importantly, they can be effective triggers for avalanches failing on the buried weak layers.

Pay attention to how the snow is changing as the day progresses. The fresh snow will be seeing lots of sunshine today, melting the surface and producing rounds of natural loose snow avalanches. Strong winds will continue to build slabs, which also may fail naturaly. Both of these types of slides can be effective triggers for much larger avalanches failing on the layers of weak snow buried in the upper snowpack. 

If you get out in the new snow today, take a minute to let us know what you are seeing out there. Your observations are a key component in an accurate avalanche forecast. Information about natural and triggered avalanches, the amount of new snow and wind, and riding conditions are all very helpful. Thanks in advance for giving your time, we appreciate you. Click here to access the observation submission page.

It has been a tragic week in the world of the snow. At least 13 people have been killed in avalanches in the Western US. You can find more information on these accidents here. Let's do everything we can to not add to that ghastly number. 

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