Bollettino valanghe

Whitefish Range

Flathead Avalanche Center
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Pericolo valanghe

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

In sintesi

Low-angled, planar slopes sheltered from the wind offer the least risky riding today. On shaded, convex slopes above terrain traps, dangerous avalanches that break over 2 feet deep are possible. You can also trigger slides closer to the snow surface on slopes that collect windblown snow. This hazard is more widespread at upper elevations and in the central and northern parts of the range.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    It remains possible to trigger avalanches that break 18 to 30 inches deep on weak snow buried in early December. This threat is most widespread on upper-elevation, shaded slopes. It is isolated on mid-elevation and sunny slopes. 

    Recent observations have shown some variability in the sensitivity of this layer. No propagation in the Link Lake area Tuesday where the layer was clearly visible, but propagation with relatively small forces further southeast on Saturday. The kicker is that any triggered slide will be very difficult to escape and involve more than enough debris to bury or injure a person. A classic low-likelihood, high-consequences dilemma. 

    The most straightforward way to manage this lingering hazard is to avoid riding on or below steep, shaded slopes. If you choose to step out, you can reduce the chances and consequences of a nasty surprise by avoiding steep, convex slopes above terrain traps like trees, rocks, and gullies. Slopes with variable snow depths are pockmarked with unidentifiable trigger points. These slopes are often scoured and loaded by cross-slope winds. 

    (12/21/2024)

    The image shows a large avalanche that failed naturally in the central Whitefish Range. This avalanche failed on a north facing slope at upper elevations. 

  • Wind Slabs

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

    The hazard of triggering slabs of drifted snow exists in the terrain that harbors the persistent slab avalanche problem. It is most widespread in the central and northern parts of the zone, where a combination of new snow and gusty winds is forming slabs of wind-drifted snow. Look for these top-loaded onto lee slopes and chutes, and cross-loaded into gullies. Debris from falling cornices and wind slab avalanches can release slides that break deeper in the snowpack, on the early December persistent weak layer. 

    Cornices overhanging a slope, whale-shaped drifts, and blowing snow are signs of this hazard. Avoid steep slopes with more than about 8 inches of stiff, wind-blown snow.  Play on gladed, low-angled slopes that are sheltered from the wind. This may include slopes that face into the sun today, since last night's snowfall buried any suncrusts.

    (12/20/2024)

    A small wind slab is visible just beneath a cornice near the summit of Elk Mountain. This slide likely failed during the intense wind event of 12/17-18. 

    Photo: Mark Dundas

Avalanche Discussion

Oh, the weather outside’s been frightfulA wintery mix is not delightfulAnd since we need places to go Let it snow, let it snow, let it snow

The slabs show signs of settlingAnd weak grains look less threateningSome brush and stuff down lowLet it snow, let it snow, let it snow

When it finally dumps all nightHow we'll love going out for some turnsBut if we wanna get home all rightWe take an avalanche class and learn

The seas are slowly heatingAnd, darn, winter feels so fleetingBut ARs help the snowpack growLet it snow, let it snow

For the tune, choose a jaunty version by Dean Martin, or a snowpack melter by Doris Day.

Happy Holidays.

Regioni coperte