Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
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Peligro de aludes

Tue
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 7 months ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

You could trigger an avalanche on a buried weak layer where the surface snow has stiffened. Reports of a remote-triggered slide, shooting cracks, and poor snowpit test results indicate that slabs may be sensitive to the weight of a rider. Choose a low-angle slope not connected to steeper terrain for a safer experience.

The danger is higher in the Swan Range, where a widespread buried layer of surface hoar has created dangerous avalanche conditions.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Recent warming and wind have formed a surface slab that caps a weak layer (facets or surface hoar) and crusts on multiple slopes. Observers report shooting cracks, poor snowpit test scores, and a remotely triggered slide (See adjacent image).  The weak layer is found within the top foot of the surface in sheltered locations and buried 2 to 3 feet deep on wind-loaded slopes.

    Slides can be triggered remotely from flat terrain above, to the side, and below steep slopes. 

    Look and feel for dense surface snow where your skis, board, or machine do not sink in as deeply. Cracks beneath you indicate you have found a slab, while cracks shooting away from you indicate a sensitive slab. This is a near-surface problem, and hand pits are a good way to confirm the presence of surface hoar.

    Seek out softer snow and low-angle slopes for a safer and more enjoyable experience. 

    Storm or Wind Slab: The Flathead Range was favored with up to 5 inches of dense snow recorded at the Tunnel Ridge snow station. Riders may encounter slab-like conditions in the new snow. Expect to find up to a foot of drifted snow on the leeward slopes that may be reactive to your weight. A triggered slide in the new snow may initiate an avalanche on a buried weak layer, resulting in a larger slide.

    (1/31/2026)  This small soft slab avalanche was triggered by a motorized rider in the northern Whitefish Range on Saturday. This likely failed on the buried weak snow + crust setup. Riders could trigger slides similar to, or larger than, this one today.

Avalanche Discussion

Tricky avalanche conditions are developing across the area as weak snow and crusts formed during the January drought are now capped by a slab in many locations. This morning, we transitioned from a Storm Slab problem to a Persistent Slab problem in all zones. We are keeping the danger rating at CONSIDERABLE in the Swan Range today, with the plan to drop to MODERATE on Tuesday.

Swan Range - A widespread, well-preserved surface hoar layer was the culprit in two remotely triggered slides on Friday and Saturday (Observation, Observation). The Swan Range remains our primary concern because surface hoar may persist for extended periods, can be remotely triggered, and produce avalanches wider than expected.

Whitefish Range - Friday, observers noted long shooting cracks in the surface slab that became cohesive during the mid-day warm-up (image).  On Saturday, a motorized observer triggered a small, soft-slab avalanche in the northern part of the range (Observation). This slide most likely failed due to the weak-layer + crust setup, but did not propagate widely because of the soft nature of the overlying slab. On Sunday, Rob and Lloyd conducted a FOFAC Level 1 motorized class in Kimmerly Basin (southern Whitefish Range), where they obtained pit results of ECTP 1 and 2 on buried surface hoar 15 cm down on a mid-elevation north aspect.  At the same time, a Level 1 avalanche class noted a developing surface slab (image) in the southern Whitefish Range. 

Flathead Range/southern Glacier Park - Challenging access has limited observations from this zone. Josh and Mike traveled to the Skyland area on Sunday and found buried surface hoar under 4-6" of recent soft snow. The only locations where this weak layer was a concern were along ridgelines where the wind had stiffened the recent snow into a slab (Observation). An experienced group visited southern Glacier Park and encountered a variety of snow conditions. Above 6000 feet, a very thin crust capped 3-8 inches of soft snow. Lower down, corn gave way to mank, ending with substantial blow-down on the valley floor (Observation). 

February 2nd is Groundhog Day, the midpoint between the shortest, darkest day of the year on the winter solstice and the spring equinox.

 

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