Bulletin d’avalanche

Whitefish Range

Flathead Avalanche Center
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Danger d’avalanche

Fri
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Complex and dangerous avalanche conditions are developing due to changing weather. Triggering an avalanche failing 1 to 3 feet deep is likely. Avalanches may fail naturally and run long distances. Plan a simple day as extreme cold will complicate any rescue effort.

Conditions in the Ten Lakes area, in the northern Whitefish Range, may be more dangerous because more snowfall has created thicker slabs.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1.5–2.5

    Yesterday, many stations saw winds shift to easterly. More will follow suit today, resulting in thin and sensitive slabs on atypical slopes (Southeast, through West, to Northwest). Expect to find slabs of drifted snow near ridgelines, saddles, in cross-loaded gullies, and on cutbanks further downslope.

    Extreme southwest winds during the previous two days formed hard slabs on typical leeward slopes (Northwest, through East, to Southeast). These can break well above you, wider than expected, and are very difficult to escape. Fresh snow can conceal slabs formed earlier this week. You’ve found a hard slab if you notice your boards or machine riding on top of a dense, drum-like layer of snow.

    (1/10/2024)

    Blown in crown from natural slab avalanche triggered by cornice fall.  Likely ran during 1/6 cycle.

  • Storm Slabs

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

    As you seek out wind-sheltered slopes, watch for collapsing or cracking under your feet or machine. Choose terrain less than 30 degrees in steepness where you experience these warning signs. Storm snow is piling up deep and may rest on persistent weak layers. The distribution of these weak layers is not clear yet. Slabs may break wide distances and be triggered remotely.  

    (1/10/2024) Small slab avalanche just east of Marias Pass

Avalanche Discussion

“Wind is the architect of avalanches” – Wilhelm Paulcke, circa 1926

There is a new architect in town as arctic air sets into the advisory area. The well-advertised arctic front arrived at Marias Pass yesterday (Wednesday) morning and made its way down into the Flathead Valley.  Currently, it’s stalled out somewhere between Kalispell and Bigfork but should resume its progress south today. As the front passes, many stations have seen winds shift to northeasterly.  Some, like at WMR, are holding out with prevailing southwesterlies.  Others, like Aeneas Ridge in the Swan Range, or Hornet in the northern Whitefish Range are eerily calm. Ultimately, I’d expect winds to start forming thin, reactive slabs on slopes where you normally wouldn’t find them. Old, stubborn slabs likely remain on typical lees, particularly at upper elevations.  This was case in John F. Stevens Canyon yesterday.

Storm snow is still stacking up throughout the advisory area. We’ve expanded the storm slab problem to lower elevations for all zones. Stahl Peak in the northern Whitefish Range picked up over 1.0 of SWE in the last 24 hours and nearly 12 inches of snow.  This brings the total SWE to over 4.0 inches for this location since January 4th.  Default to low-terrain if you’re traveling in this area.

Extreme cold is a hazard in its own right, and a good reason to plan a simple day with wide margins for safety.  Stay warm!

Régions couvertes