Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Avoid areas where you see snow being transported into dune-shaped drifts. A hard wind slab may step down to a deeper buried weak layer, causing a large and dangerous avalanche. Seek out slopes sheltered from the wind for a relatively safer experience. New snow and wind overnight may increase the avalanche danger to CONSIDERABLE.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Relentless moderate and strong winds out of the southwest continue to drift snow into firm slabs. Hard slabs of drifted snow can break above you and easily sweep you off your feet. These will be more sensitive to the weight of a rider where they rest over buried weak layers.

    Identify areas of concern by textured surfaces or dune-shaped drifts. Cracking around your feet or machine is a sign that slabs may be ripe for human triggering. Utilize small, inconsequential terrain features with a partner in a safe location to test how sensitive new slabs of drifted snow are. Sticking to slopes sheltered from the wind will offer a better and safer experience.

    (2/5/2023)

    A rider triggered this wind slab from a convexity. The slab broke above the riders, catching and carrying two down the slope. Thankfully, no serious injuries were sustained. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Buried layers of surface hoar and facets rest 2 to 4 feet below the surface. Avoid common trigger points on the slope by steering around steep break overs or possible thin spots. If triggered, slabs may break wide distances and be difficult to escape.

    All reported avalanches in the last month are on north through east-facing slopes. The last reported avalanche likely failing on this layer was on January 25th. Since then, snowpit tests have shown a mixed bag of propagating and non-propagating results. 

    (1/30/2023)

    Snow Profile in the Swan Range. Hard force ECTP30 on a weak layer 90cm below the surface.

    Photo: sw

Avalanche Discussion

A pacific cold front approaching the forecast region tonight will increase the avalanche danger. Forecast models show precipitation to start around 6 pm and continue into tomorrow morning. Snow totals throughout the forecast area will hopefully average around 8 to 12 inches of new snow. Moderate and strong southwest winds will accompany this precipitation. Plan for the avalanche danger to rise to CONSIDERABLE overnight. The current avalanche danger reflects what we expect during daylight hours.

Since February 1st, southwest winds have blown steady at moderate (17-25 mph) and strong (26-39 mph) speeds. Generally, wind speeds averaging in the moderate category are optimum for building wind slabs when there is snow available to transport. Dribs and drabs of snow over the past week have offered fuel for winds to drift snow into firm slabs.

There is no shortage of observations of wind-drifted snow. Both natural and human-triggered avalanches have occurred in the past week. A group of riders triggered a wind slab on a convexity in the Flathead Range on Sunday. This is a flashing light for all of us to continue to avoid wind-loaded slopes. Wind slabs may break wider and further above us where they rest on a slick crust or a persistent weak layer.

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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