Lawinenlagebericht

Swan Range

Flathead Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 4 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

You will find dangerous avalanche conditions at upper elevations, as a result of southwesterly winds and new snow.  Steer around these freshly built slabs on leeward slopes and ridgelines. Consider the consequence of a slide before committing to avalanche terrain.

Lawinenprobleme

  • Wind Slabs

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

    Southwesterly winds will continue transporting the new snow near and below ridgelines into 1 to 3-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. 

    Overnight, weather stations recorded sustained winds capable of transporting snow in all forecast zones. Moderate winds with strong gusts are expected today and, thus, will continue to blow snow into firm slabs. Cracking around your machine or boards is a clue that you've found an unstable slab. Pay attention to the consequences of being caught in even a small slide, as terrain features can amplify the consequences with rocks, cliffs, trees, and other terrain traps.

    (2/6/2023)

    Blowing snow in upper elevations.

    Photo: Kevin Oberholser

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–3

    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 Flathead Range and southern Glacier Park and 2-4 feet below the surface in the Swan Range. This recent snowfall and wind may test buried facets and surface hoar.

    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.

Avalanche Discussion

Both natural and human-triggered avalanches have occurred in the past week. Yesterday, Cam was in the northern Swan and observed five (D1 to D1.5) natural avalanches at 7000 feet over the past few days. Based on these slides being located on steep north-facing slopes, Cam inferred that these were likely wind slabs. Additionally, two riders were caught and carried over a cliff band by a small (D1) avalanche in the Flathead Range on Sunday. This avalanche was a striking example of how a relatively small slide had amplified consequences due to the cliff band below. Wind slabs have been listed as our primary avalanche problem for the past week, and with the sustained winds we’ve had overnight and forecasted for today, you can anticipate that wind-drifting and wind-loading will continue. 

To give you a snapshot of last night’s storm, here are the totals for snow and wind:

Swan Range:

  • Snow overnight: 4 to 6 inches
    • Winds: SSW averaging 22 mph, with gusts recorded up to 61 mph.

Whitefish Range: 

  • Snow overnight: 4 to 6 inches of new 
    • Winds: SSW averaging 12 to 19 mph, with gusts recorded up to 63 mph.

Flathead Range: 

  • Snow overnight: 6 to 10 inches
    • Winds: SW averaging 15 mph, with gusts recorded up to 66 mph.

 

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.

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