Bollettino valanghe

Flathead Range & Glacier NP

Flathead Avalanche Center
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Pericolo valanghe

Sat
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Human-triggered avalanches are unlikely on most slopes. Buried weak layers are gaining strength and melt-freeze crusts 4-20 inches below the snow surface make triggering a weak layer less likely. You can cause loose dry snow avalanches on very steep, northerly slopes where the near-surface snow is cohesionless. These can be dangerous if they carry you through rocks and trees, over a cliff, or into a gully.

Problemi valanghivi

  • Persistent Slabs

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

    The hazard of triggering a large, hard slab avalanche remains unlikely on isolated slopes at upper elevations. These can break on weak layers of snow buried in late November and mid-December. Stout melt-freeze crusts or ice lenses near the snow surface reduce the likelihood of a rider collapsing these layers. Slopes where the crusts are thinnest – and where the snowpack is generally shallow – are where you have the greatest chance of triggering a large avalanche. Travel one rider at a time where this hazard lingers.

    (1/4/2023)

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    The last decent shot of snowfall occurred Saturday, six days ago. However, as the surface snow continues to facet and weakens, triggering Loose Dry sluffs on steep, shaded slopes remains possible. These will be most common on slopes, 40 degrees or steeper harboring 8 inches or more loose snow. Choose terrain with runouts free of surface obstacles that could result in trauma if you lose your footing. Steering around slopes above cliffs or ending in a gulley-like feature where the snow can pile up deep will minimize your exposure to this problem.

    (1/4/2023)

    A skier-triggered avalanche involving cohesionless snow above Marion Lake in the Flathead Range. These will become more widespread as the near-surface snow facets. 

    Photo: Paul Fotter

Avalanche Discussion

The green light comes on and everyone scatters into the alpine.. yet, observations have steadily declined with each day in the new year.  I’m optimistic that’s because you’re all stepping out on multi-day epics and center-punching the steeps. Don’t worry, I’ll be here when you get back; just waiting to hear how it was and what you found.  

We’re not picky when it comes to observations.  Reports of stable conditions are still useful when producing the daily forecast.  Details regarding the current snow surface are even better.  Reports of faceting, surface hoar, and crusts help us map potential weak layers before they get buried. As we move into new terrain it’s likely we’ll continue to find more evidence of the late-December cycle like this one Link Mountain.  Even though this cycle is well behind us,  this information helps us better understand the weak layers from late November or mid December. Also, its possible you might spot one of the many glide cracks/avalanche that have opened up throughout the advisory area.

 One area where we’re clearly lacking information is the upper extent of the crust resulting from the Christmas rain event.  So far this crust has been documented on all aspects and elevations, however, above 7000 feet it appears to fade into a thin lens. If anyone out there is setting this season’s elevation record, I suggest you take the time to dig down and see if this crust is present.  If it’s not there, I’d be more skeptical of the buried weak layers, particularly in areas with a comparatively thinner snowpack. Remember: low danger doesn’t mean no danger.

If you have been waiting for a low danger rating to start your backcountry season, be sure to  thoroughly check your gear and refresh your skills.  The beacon parks at Whitefish Mountain Resort are an excellent spot to practice companion rescue.

Regioni coperte