Bulletin d’avalanche

Whitefish Range

Flathead Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

West winds are increasing today and will continue to transport the recent snowfall. Expect to encounter 1-foot thick wind drifts forming below ridges and cross-loaded features in upper elevations. If the sun comes out and you see roller balls or moist surface snow, move to shaded slopes to reduce your risk.

Problèmes avalancheux

  • Wind Slabs

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

    Southwest winds will continue transporting the recent low-density snow near and below ridgelines into 1 to 2-foot slabs. To find these, use your hand or ski pole to feel the texture of the near-surface snow. If it is stiffer or more consolidated, you've found a drift that may be dangerous if it's on a slope steeper than about 35 degrees and more than about 8 inches thick. Yesterday, observers noted pockets of stiff snow mid-slope that were relatively harmless but sensitive to a rider's weight. Pay attention to the consequences of being caught in even small slides in terrain with rocks, cliffs, trees, and terrain traps.

    (2/1/2023)

    Obivous signs of wind-drifted snow that pointed us to terrain sheltered from the wind. 

    Photo: Cam

  • Persistent Slabs

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

    Observers continue to find layers of buried weak snow that are reactive in snowpit tests. This layer is most prevalent on shady aspects 1-2 feet below the surface in the Whitefish Range, Flathead Range, and southern Glacier Park, and 1-3 feet below the surface in the Swan Range. Buried facets and surface hoar appear to be slowly gaining strength, but recent snowfall and wind continue to test this layer. A surface slide has the potential to step down to this layer, triggering a much larger slide. Continue to choose lower-angle terrain free of overhead hazards and convexities. Slopes with clean runouts are an excellent way to build a margin of safety into your day.

    (1/31/2023)

    Snowpit on SE aspect in the Swan Range.  Failed on a persistent weak layer 50cm from the surface,  ECT20.

    Photo: sw

Avalanche Discussion

Today's avalanche problems are similar to yesterday's and are fitting for both Groundhog Day (today) and the classic film Groundhog Day with Bill Murray.

Observers reported mostly harmless, small human-triggered loose dry avalanches across our forecast regions yesterday. These riders managed their risk by avoiding wind-loaded slopes and minding their sluff. Instabilities observed were limited to cracking in small, soft wind slabs and isolated collapses in older wind slabs.

Tuesday’s low-density, cohesionless snow was transported by southwest winds, especially along the Aeneas Ridge, the Flathead Crest, and higher elevation ridgelines. Cloud cover and cool temperatures slowed the settlement and cohesion of recent snow, as many underlying surfaces are hard windboard or slick crusts. There is a chance for partly sunny skies and warming today, which could moisten the cold, dry surface snow for the first time, increasing the chance of natural loose avalanches. So, pay attention to what’s above you, and once you notice a moistening of the snow surface or rollerballs developing, limit the time you spend on or under steep sunny slopes. 

As we enter the month of February, the Flathead Basin is 98% of the 1991-2020 median for SWE. The FAC forecast area contains 5 SNOTEL sites at low and mid-elevations. All sites are below the median, except Noisy Basin reporting the highest at 107%.

  • Northern Whitefish Range: Grave Creek is 76%, and Stahl Peak is 86% of the median.
  • In central Glacier Park: Flattop is 82% of the median.
  • Hungry Horse Reservoir: Emery Creek is 74% 
  • In the northern Swan Range: Noisy Basin is 107%

Come one, come all! Flathead Avalanche Friends Fest, a four-day festival from Feb 8-11, has a full schedule with mini-clinics, a keynote speaker, après, and a Big-A$$ Raffle. A little something for everyone. We hope you can join us to celebrate our community, learn about snow, and support our safety mission. Learn more here.

Motorized Level 1 - Instructed by Eric Knoff and Six Points Avalanche Education from Tuesday, February 7, 2023, to Thursday, February 9, 2023. More details are here.

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