Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
Auf der Karte ansehen

Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
Open full map
Veraltet — dieser Lagebericht ist 8 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Adjust your tactics and mindset as you climb or descend.  At upper elevations, you can trigger slabs of drifted, dry snow that may be dangerous where they are 8 inches or more thick. At mid-elevations, triggered wet loose avalanches are possible on very steep slopes with 8 inches or more of saturated surface snow.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Above about 6500 feet, freshly-formed slabs of drifted snow will be sensitive to the weight of a rider or snowmachine today. These can be dangerous where they're 8 inches or more thick. They'll be more widespread if the snowfall forecasts for today verify. 

    Look for these slabs on steep slopes that collect wind-blown snow, like the downwind sides of saddles between peaks, the tops of chutes, and the lee sides of corniced ridges. The slabs will feel dense or firm compared to undrifted snow. They may have irregular surfaces, with dunes or scalloped edges. Cracking that shoots away from you or your machine is a clear sign these are unstable.

    Drifts resting on buried surface hoar or facets may respond unpredictably to your weight. That is, they may release remotely - from the sides, from below, or from some distance away. And they make break wider than expected or wrap around terrain features. Factor these wild cards into your approach to potentially wind-loaded terrain. 

    (4/23/2025)

    Slopes with wind-textured surfaces or below cornices are where you are most likely to trigger sensitive slabs of wind-drifted snow. 

    Photo: Rob Millspaugh

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    The steeper the slope, they more likely you are to trigger a sluff of dense, wet snow.  These may range from harmless roller balls to gooey bulldozers that can plow you off your feet. The hazard will be most widespread in areas that have received the most rain since Friday night, and where rain continues today. That's likely the northern Whitefish Range and the Flathead Range.

    Loose wet snow slides can be dangerous on slopes where there's 8 inches or more of wet, sticky snow above the firm Christmas Crust. And above terrain traps that exaggerate the consequences of getting plowed downhill (see video). Rollerballs fanning out from your feet or machine as you sidehill, climb, or descend are a good clue that the wet snow is unstable. 

Avalanche Discussion

I don't remember another winter when freezing levels jumped up and down so often or so dramatically. Sure, it rains regularly when storms arrive from the southwest. While that's typically a low-elevation problem, sometimes the rain line climbs high. And my sense is that the warm, wet storms are distinct events, staggered throughout the season. But the back-to-back-to-back rain and warming with only a day or two of cold conditions in between? For a month? That seems very unusual. Mark summarizes the results - stark disparities in snowpack with elevation - in this video. 

A few days ago, after reports of large, upright surface hoar on shaded slopes throughout the region, I was preparing for a classic Flathead area avalanche problem - incremental loading leading to a lingering Persistent Slab avalanche hazard. But that concern is moot, at least at mid elevations, after rain showers, warm temperatures, and high freezing levels Saturday and today. That combo destroyed the surface hoar and facets on many slopes below about 6500 feet, and natural wet loose snow avalanches have filled many steep mid- and low-elevation gullies with dense debris piles. So at mid-elevations, mitigating a wet snow avalanche hazard is again the primary focus.

Upper elevations - above about 6500 feet  - did get some snow. And moderate, gusty winds. That's a combo for a distinctly different avalanche problem - wind slabs. Perhaps an unpredictable one in places where recently-buried surface hoar and facets remain intact. You'll need to manage this hazard very differently, and these wet/dry, loose/slab roblems may make for some complex travel as you transition between mid and upper elevation slopes today and tomorrow.

 

 

 

 

Abgedeckte Regionen