Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

Sustained winds out of the southwest continue to form hard slabs of drifted snow. Avoid areas where you see snow being transported into dune-shaped drifts. Give slabs of wind-drifted snow a wider margin for error if you find them resting over a weak layer or slick crust. Relatively safer riding conditions exist in areas protected from the wind. New snow and wind overnight may increase the avalanche danger to CONSIDERABLE.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    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 or a slick crust.

    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

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    A facet/crust combination buried 1 to 2 feet below the surface remains a concern. This layer is slowly getting loaded by wind-transported snow and dribs and drabs of new snow. Give areas where this layer exists a margin for error, especially where winds drifted snow into a more cohesive slab. Selecting slopes free of convexities and slopes with smooth runouts are two ways to build in those margins to your travel day. 

    (2/4/2023)

    The current Persistent Slab problem involves facets beneath a crust formed in mid-January.

    Photo: Dundas

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

Regioni coperte