Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Safely enjoy today’s sunshine by recognizing—and steering away from— wind-drifted snow along alpine ridges. Use small and inconsequential slopes to test recent snow before committing to steep terrain. Reduce the consequences of a slide by limiting travel above hazards like gullies and cliffs.  

Problemas de aludes

  • Wind Slabs

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

    You can find slabs of wind-drifted snow on slopes that are usually windward due to recent northeast winds. Most will be small and tough to trigger, though they can have big consequences in extreme terrain or terrain traps. Decreasing windspeeds should limit any growth today. 

    Identify wind-affected snow from surface clues like a rippled surface or pillowy, dune-shaped features.  Expect to find these along ridgelines, gullies, and other prominent terrain features. Cracking around your boards or machines indicates that wind-blown snow is sensitive to human triggering. Pick lines that aren't above cliffs, rocks, gullies, and trees, so you're less likely to be buried or injured if surprised by a slide.

  • Persistent Slabs

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

    It is still possible to trigger a slab that breaks 18 to 24 inches deep on thin layers of weak snow above the very hard, early February ice and crust layer. These layers are better developed on shady, upper-elevation slopes but are also found on isolated sunny and mid-elevation slopes. 

    Opt for planar slopes (with constant slope angle) rather than those with break-overs where the slope abruptly steepens. Limit the consequences of any slides by choosing slopes free of gullies, rocks, and trees. Whumpfing collapses and shooting cracks are clear signs of unstable structures. When in doubt, you can further reduce your risk by defaulting to less steep terrain. 

    (2/14/2024)

    Near surface structure in pit at 7000', South aspect. Buried surface hoar on the 2/8 crust was not standing up and was decomposing.   ECTX, CTX.

    Photo: Rob Millspaugh

Avalanche Discussion

Dry conditions today should keep us on a trend toward stability.  Snowfall from early this week continues to settle on top of the remarkably stout and well-documented crust from early February.  However, weak faceted snow and patchy surface hoar on or near this crust remain a concern, particularly on shaded slopes above 6500' (where we've had limited recent observations). The last reported activity on these layers was Tuesday (Flathead Range, here). Wednesday, several parties felt comfortable transitioning to a "stepping out" mindset by riding slopes greater than 30 degrees in steepness though they still avoided likely trigger points and terrain traps. With great riding conditions and forecasted blue skies, I expect folks will be getting after it today and tomorrow.  If you're one of those folks, consider starting small before committing to larger and steeper slopes.  Also, let us know what you find during your travels: we received no observations from yesterday. Even reports of benign conditions are useful.

Our Canadian neighbors are reporting a similar but more active snowpack.  On Wednesday, A skier near Fernie triggered a large (D2) slab avalanche on a southeast aspect at 6400'.  Also on Wednesday, explosives mitigation near Fernie produced many large (D2) avalanches in the alpine on nearly all aspects.

Upcoming event: Flathead Avalanche Friends Fest, February 21-24. We have four days of events on tap for you: Beacons & Brews, Name That Tune/Name That Avalanche, Workshop Night with State of the Snowpack and USGS, Hot Dog Days, and the Ultimate Après with Backcountry Partner Speed Dating and the Big A$$ Raffle. More info at flatheadavalanche.org/event/friendsfest

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