Bollettino valanghe

Rattlesnake

West Central Montana Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
Senza grado
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Non aggiornato — questo bollettino è scaduto 7 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The storm arriving today will be the first test of the weak layers that formed during the January drought. Triggering an avalanche will be possible anywhere the new snow forms a slab 6" or more above buried surface hoar or buried near surface facets. If you experience collapsing, whumfing, or shooting cracks, stick to slopes less than 30 degrees in slope angle. 

Mid elevation terrain is cooling, but the lack of a solid refreeze last night will keep wet snow avalanches possible today. If you are sinking into wet and unsupportable snow, stay out of avalanche terrain. 

Low elevation terrain does not have enough snow to produce avalanches, and there is minimal terrain where an avalanche can run from mid elevation into low elevation. 

Problemi valanghivi

  • Persistent Slabs

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

    3-6 inches of new snow is expected today for upper elevations in the Bitterroot. With moderate winds expected, this will create slabs up to a foot deep along ridgelines and at upper elevation. The reason these we are not calling them wind slabs is that they are less likely to fail at the new snow interface, and more likely to break 2-8 inches below the current snow surface on layers of buried surface hoar and buried facets. 

    The warm weather and sun helped destroy large areas of buried surface hoar on solar slopes. Even lower angle north facing slopes got enough sun to affect the buried layers and make them less continuous. Having said that, a common trap with surface hoar is to dig high in start zones and not find it, then descend part way down the slope and trigger an avalanche on buried surface hoar. It can get destroyed high on slopes but preserved lower on the slope creating tricky conditions for slope level snowpack assessment. 

    Identify buried surface hoar by digging into the snowpack and looking for a thin grey line 2-10 inches below the snow surface. Buried near surface facets will present as weak sugary snow crystals buried in the top portion of the snowpack. If you either problem with a slab above it in your snowpit, or experience collapsing or whumfing on it, stay off slopes over 30 degrees.

    Expect the problem to become more reactive through the day as new snow accumulates. By tomorrow, we expect it the likelihood to increase significantly as the storm continues. 

    (2/6/2026)

    Large 2-4 cm surface hoar buried on a NE aspect at 7800 ft

    Photo: Arden Feldman

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Mid elevation terrain is still wet due to a lack of a refreeze last night (or any night for the past 5 days). The chances of a larger wet snow avalanche running into this terrain from upper elevation has decreased with cooler temperatures. 

    • Mid elevation West-South-East aspects do not have large amount of snow in the start zones. The snow in these areas is saturated with water all the way to the ground. You are likely to trigger an avalanche in steep areas of this terrain, but avalanche size will be smaller. Keep in mind if a small avalanche runs into a terrain trap, it will still be able to bury you.
    • Mid elevation north aspects are where the most variability lies. Without direct sunlight, start zones with tighter green trees are much more wet than steeper open terrain. This has to do with the energy (radiation) balance within the snowpack. Snowpack totals on this aspect/elevation vary across zones and while some slopes have large amounts of snow in start zones, other areas are near dirt. The key takaway is that if you are sinking into unsupportable snow, stick to lower slope angles where wet snow avalanches will not run as easily.

    (2/6/2026)

    Human triggered wet loose avalanche on an upper elevation southeast aspect in Jenny Bowl

    Photo: Arden Feldman

Avalanche Discussion

Finally a pattern shift! Today is the beginning of a series of storms and by Wednesday most upper elevation terrain should receive a foot or more of new snow. This will be the first test of multiple weak layers that formed in January. With that, it is time for a change in mindset. 

For the past weeks, we have been in a moderate or low danger mentality with the ability to ski or ride most any terrain. With the arrival of this storm it is time to step back and change our mindset to a more conservative a approach. Careful snowpack and route selection will be necessary until we figure out how reactive the buried weak layers will be to this new snow load. 

Glide cracks are opening up throughout all zones. Glide cracks are very unpredictable and can fail minutes after the crack opens, or months after. Avoid spending time under open glide cracks. Cornices have potential to break off naturally during periods of warming throughout the spring. Minimize the time you spend underneath overhung cornice on warm days. 

Avalanche education is a lifelong journey built on developing sound judgment, gaining experience, and applying repeatable decision-making systems in the backcountry. Our American Avalanche Association (A3) recognized Level 1, Rescue, and Level 2 courses are offered throughout the winter and help you travel smarter in avalanche terrain. Explore current courses and registration on the Education page. 

Please continue to submit observations and ski and ride safe!

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