Lawinenlagebericht

Rattlesnake

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

Triggering an avalanche is possible anywhere the new snow has been blown into drifts six inches deep or more. Fresh snow may hide older wind slabs from the past 72 hours, which could create large avalanches if triggered. Watch for red flags like shooting cracks, collapsing, or recent avalanches. If you see these, stick to slopes less than 30 degrees.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    In the past four days the Rattlesnake has received 18 inches of snow (1.9 inches of water) with moderate westerly winds. This is the ideal recipe for building wind slabs on easterly slopes. Both natural and human-triggered wind slabs have been reported in the past three days. Click here for an avalanche observation from Point Six.

    While we don’t expect new wind slabs to form today, triggering a wind slab from the past few days is still possible. Identify wind slabs by looking for pillow-shaped deposits and drifts.  They are most likely to form just below ridgelines, below roll-overs, and in cross-loaded gullies. Avoid slopes over 30 degrees where you see signs of wind loading.

    (1/7/2026)

    A wind slab human triggered by cornice on an upper elevation east aspect

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1–2

    At high elevations we’ve found small facets buried just over a foot deep. These facets formed on the snow surface in late December and early January, before being buried by this week's snow. We have had no reports of avalanches on this layer, but we’ve gotten propagation in snowpack tests.

    On solar aspects the sun likely destroyed any facets before they were buried. So, look for this weak layer on high-elevation shady slopes.

    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 layers before committing to a line. Strong over weak snowpack structure or propagating extended column tests indicate you should avoid slopes over 30 degrees.

    Deeper buried crusts are still present in the Rattlesnake. However, with no avalanches on them yet this season, we are not worried about them as weak layers at the moment.

    (1/7/2026)

    Snowpit on a north aspect at 7800 ft in the Rattlesnake

Avalanche Discussion

Snowfall is coming to an end, and we’re moving into a period of high pressure for the weekend. As we put time between ourselves and the storm, the snowpack’s sensitivity to triggers will decrease. However, lingering wind slabs will remain possible, and a few buried weak layers still have our attention.

With limited observations, uncertainty exists regarding the near surface facets buried about a foot deep. They formed during the New Year’s dry spell, and are likely only preserved where the snow remained cold. We haven’t seen avalanches on this layer, however visibility has been limited. Up near Whitefish, a skier triggered an avalanche on what appears to be the same layer. Click here for more information.

The weak layer in the Southern Bitterroot is associated with a crust buried on December 26th, with underlying facets. While this crust exists in the rest of our forecast area, we haven’t found such obvious facets underneath it elsewhere. Snowpack tests have found propagation under this crust in the Southern Bitterroot only.

Clearing weather will give us a chance to look around for fresh avalanches. If you see any, please let us know. If you dig in the snow, please let us know what you find. Tests are helpful but not necessary, even a photo of your snow pit wall is useful. Your information helps us reduce uncertainty, which leads to a more accurate forecast.

 

On January 5th, a snowmobiler was killed in an avalanche near Lake Tahoe. Our condolences go out to the family and friends. If we look at the preliminary accident report, we find terrain and wind slab avalanche size that resembles much of the motorized terrain in our forecast zones. We mention this as a reminder and learning opportunity that even small avalanche paths can be dangerous if they could push you into trees or other terrain traps. 

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