Bulletin d’avalanche

Rattlesnake

West Central Montana Avalanche Center
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Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 7 months ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Human triggered wet avalanches are likely, and natural wet avalanches are possible. Look for recent avalanches, roller balls, and wet mushy snow. If you see any of these signs of instability, stay off slopes over 30 degrees and away from their runouts.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2

    Wet snow exists on all aspects and elevations and will be reactive to human triggers. Natural wet avalanches are also possible. Wet loose avalanches and roller balls were observed throughout the region yesterday. (See observations here.)

    If you see rollerballs, or find yourself sinking 6 inches or more into wet snow, it is time to get out of avalanche terrain altogether. When temperatures are this warm, shaded aspects will be wet too, so you can’t rely on simply moving out of the sun. At most low elevations there is not enough snow for an avalanche. Stay out of gulleys and creek beds where you do see low elevation snow.

    Overnight temperatures remained above freezing at middle and high elevations. This limited snow surface refreeze. While early morning travel is often a viable strategy to avoid wet avalanches, that is not the case today. You may see a thin surface refreeze, especially at valley bottoms where temperatures were cooler, but these crusts will break down quickly as the sun comes out and temperatures rise.

    (2/4/2026) Wet loose activity

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    A weak surface hoar layer from our January drought was buried about a week ago. In most places it is only two or three inches deep under soft new snow. However, in wind loaded areas it could be 6-10 inches deep. In these isolated places it will be reactive to human-triggering.

    Cracking and collapsing are always signs to stay off slopes over 30 degrees and away from their immediate run outs. Before committing to a steep slope, dig down and look for a thin layer of surface hoar with an overlying slab. This thin weak layer won’t always be visible to the naked eye, so you may need to do snowpack tests to find it. If you find a relatively strong slab over a weak layer, stay off slopes over 30 degrees.

    There have been recent avalanches on this layer in the Northern Swan Range. (See observations here, and here.) Compared to near Missoula, the Northern Swans received more snow in the past week (6-10 inches) and saw stronger winds. This avalanche activity could be a preview of what we’ll see once we get more precipitation.

    (2/3/2026)

    Buried surface hoar in a snowpit from the Seeley Lake region. The snowpack in the Bitterroot looks similar.

Avalanche Discussion

Our main concern today is wet snow. Thanks to a temperature inversion, high and middle elevation snow did not refreeze overnight. Any low elevation refreeze will break down quickly as temperatures warm. Without an overnight refreeze it will be difficult to avoid the wet loose problem, regardless of aspect or time of day. So, the usual strategies of travelling early and/or sticking to shady aspects will not suffice.

Wet avalanches will be largest and most dangerous where heat penetrates deep enough into the snowpack to melt buried crusts. As crusts turn back into wet melt forms, avalanches can gouge deeper into the snowpack, entrain more snow, and quickly become large.

Buried surface hoar is not yet deep enough to create a widespread problem. While the surface hoar layer itself exists on many aspects and elevations, it only has enough of an overlying slab to warrant an avalanche problem in isolated locations. These locations are wind loaded lees where the slab is harder and thicker, and high elevation areas that got more than 6 inches of recent snow. If we get more snow in the near future, we’ll likely extend the persistent slab problem onto our middle elevation band.

Glide cracks have opened up on isolated slopes throughout the region. Glide avalanches are highly unpredictable, and avoidance is the answer. If you see open glide cracks, do not travel underneath them. With warming temperatures, cornices can become weak and fall. Cornice failure is unpredictable, so avoidance is the best strategy.

Crusts associated with December rain events and warm-ups still exist in the snowpack. In some places they are associated with weak facet layers. While we have not seen avalanches on these layers, we are still keeping an eye on them.

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!

Régions couvertes