Bollettino valanghe

Swan Range

Flathead Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 8 months ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche conditions exist on isolated slopes due to strong winds and recent snowfall. You could trigger a slab 1-2 feet deep in the new snow. Steer around rollovers and wind-affected slopes, while sticking to more planar, sheltered terrain.

Problemi valanghivi

  • Wind Slabs

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

    Recent snowfall and yesterday’s (Wednesday) southwest winds created slabs of wind-drifted snow on leeward slopes. Fresh slabs may exceed 1 foot in thickness and may be triggered by the weight of a skier or rider. Open slopes below saddles and ridges are places to find these. 

    Travelling in areas unaffected by the wind will be arduous. Easier trailbreaking, where you no longer sink as deeply, textured snow, cracking underfoot, and cornices above a slope are all clues that you’re stepping onto a wind-affected slope. 

    Fresh wind slabs may have been formed on top of a buried weak layer from last week. As a result, avalanches may propagate wider and deeper than expected. Yesterday, a human-triggered avalanche in the Southern Whitefish range that failed below the new snow may be an example of this. Nobody was caught or carried, and we greatly appreciate the humility and honesty when a party relays information to us like this.

    Travel in a manner where you stick to slopes protected from the wind (treed) and steer clear of rollovers. Look for and navigate around dune-shaped drifts and seek out softer snow.

    Clues such as cracking under your skis or machine will indicate when you've found a wind slab.

    Photo: Flathead Avalanche Center

Avalanche Discussion

Anyone who was in the mountains yesterday likely enjoyed a wonderful day of powder skiing or riding. The Flathead and Glacier Park regions received over 16 inches of snow. Winds were light to moderate; however, much of the area remained sheltered, with minimal wind effects.

The Whitefish and Swan ranges still had a powder day but were slightly more wind-affected and received less snow (3-6 inches).

As the initial new snow danger begins to decrease, I’m left with a few thoughts.

  • A recently reported avalanche in the southern Whitefish Range exemplifies the need for caution around buried weak layers. The distribution and sensitivity of these are still uncertain. Reports are coming in, mostly from the Whitefish Range, of folks finding a weak layer associated with the Jan 2 warming event and the Christmas crust. The Swan range seems to have a potential for weakness on the Christmas crust. And the Flathead Range is pretty quiet. I expect this is related to limited access due to low-elevation bushwhacking and, thus, a lack of observations overall.
  • As snow accumulates and more areas open up for recreation, it is hard to temper the stoke. Continue to practice safe travel skills. Only put one rider on a slope at a time. Keep your partner in sight. Dig in the snow to look for weak layers. And practice with your rescue equipment.

Regioni coperte