Lawinenlagebericht

Flathead Range & Glacier NP

Flathead Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

While the likelihood of avalanches is gradually diminishing, the consequences of triggered and natural avalanches remain severe. An element of unpredictability makes careful travel essential. Limit your time in the runouts of steep start zones. Exit avalanche terrain early in the day. 

Lawinenprobleme

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    Triggering wet slab avalanches remains possible on steep slopes. These conditions may be most widespread where the snowpack has gradually warmed, such as shady, mid-elevation slopes and upper elevation slopes facing southeast and west. In this terrain, meltwater may still be percolating into weak layers buried around crusts that formed in December. The likelihood of natural wet snow avalanches is diminishing. However, careful route selection continues to be essential because of the potential size and consequences of slides like these. 

    Avoid traveling on or below steep start zones, particularly those under rock bands and receiving direct sun. Exit avalanche terrain early, particularly where your route will take you through the runouts of steep start zones. 

    Keep in mind that wet snow avalanche hazards can be unpredictable, particularly when inversions are present like they are this morning. Slopes with a refrozen snow surface are unlikely to avalanche, though you can't tell if these crusts exist at higher elevations. And a wet snow surface tends to give few clues to how meltwater is percolating and whether slabs are becoming unstable. 

    (1/31/2024) Peter's Ridge, Northern Swan.  Avoid traveling in or under terrain like this today.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–3

    This week's cycle of large and very large natural avalanches is clear evidence that hard slabs can break several feet deep - and hundreds to thousands of feet wide. The terrain where this hazard exists has steadily narrowed with four days of sun and unseasonably warm temperatures. However, this hazard lingers on high, shady slopes where slabs and weak layers remain dry. If you reach this terrain, beware of slopes with likely trigger points -  steep, with convex rollovers and variable snow depths. Audible collapses should send you scurrying for low angle slopes clear of overhead start zones. 

    (1/30/2024)

    The crown of a natural avalanche in Glacier National Park. It's a good example of the kind of terrain to avoid today -  steep, convex, with variable snow depths.

    Photo: Jackson George

Avalanche Discussion

It's early for Groundhog Day jokes. And conditions aren't the same as yesterday (Wednesday). Natural and triggered avalanches are less likely, though the consequences remain severe. And unlike Bill Murray's weatherman character in the classic Groundhog Day film, we can't act with impunity, knowing we'll wake up just fine tomorrow morning. 

So if you head into the mountains to enjoy the spring-like conditions, maintain safe travel practices. Natural avalanches are unlikely on most slopes today. However, there's an element of unpredictability in the ongoing Wet Slab and Persistent Slab avalanche problems. How much and where is meltwater percolating into weak layers? Which high-elevation slopes retain an unstable persistent weak layer that can propagate a collapse long distances?

Careful route selection can help mitigate this unpredictability. The most important practice today is likely to minimize time spent in the runouts of steep start zones. That reduces your chances of getting hit by wet slides from terrain that's warming and becoming unstable. And, in shaded, upper elevation terrain,  of triggering a collapse that can release a large hard slab that releases on deeply buried weak layers. 

I've heard travel conditions described as "arduous" in the past few days. Engines overheating on icy roads, thin snow cover, postholing in wet snow, delicately stepping skis across bare patches like cats through a puddle. That said, there's probably some spring corn at mid elevations where the snow surface is refreezing at night. And maybe, on shaded, moderate-angles slopes at upper elevations, some surfy dry snow. 

We're still cataloging the natural avalanche cycle that occurred early this week. For now, it appears the largest slides and most widespread activity occurred in the Swan Range near Condon. The number and size of reported slides appears to trend down as you head north, though I suspect high peaks in the Flathead Range may have seen similar slides. Scroll through the avalanches tab on our observations page. The "visual" tab gives some good charts that allow a more wholistic view of what's happened, though we are still catching up entering events. Please let us know what you see if you get out today.

 

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