Lawinenlagebericht

Whitefish Range

Flathead Avalanche Center
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Lawinengefahr

Sat
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 6 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

A recent storm on top of a weak snowpack means you could trigger a deep and destructive avalanche failing on weak layers buried 1-4 feet down. Stick to simple terrain and avoid steep slopes and their runouts, big or small.

Lawinenprobleme

  • Persistent Slabs

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

    Buried weak layers have been producing large to very large avalanches for over a month, most of them remotely triggered. Several have snapped mature trees, and many have broken back into very low-angle terrain. Slides were becoming slightly harder to trigger before the recent storm; however, a significant load of rain and snow has been added to slopes harboring buried weak layers. This new weight will stress those layers again, and so far they’ve shown little ability to handle even a modest new load. The additional weight of a person today could be enough to tip the balance.

    Managing this problem comes down to staying completely out of its reach. You might see warning signs like cracking or collapsing—or you might not. It doesn’t really matter; the structure stinks, and the consequences are high. Triggering a slide is most likely where the snowpack is thin, and the weak layer is close to the surface, such as wind-scoured slopes and those peppered with rocks. The safest approach is to avoid steep avalanche terrain altogether and give runout zones, ridge crests, and the margins of avalanche paths plenty of space.

    (3/5/2026)

    A view of the flank of a very large (D3) avalanche remotely triggered on February 21. The slide failed on the preserved surface hoar layer from the January drought.

    Photo: Mark Dundas

Avalanche Discussion

When the snowpack is the question, terrain is the answer. For over a month, the snowpack left little doubt: consistent whumpfing and remote-triggered avalanches screamed: “stay out.” Before this storm, things quieted a bit, tempting a false sense of security. But the mountains roared to remind us how untrustworthy this snowpack is, with four large to very large remotely-triggered avalanches over three days.

New loading adds fresh questions. Sensitivity may wane, only to spike again under added stress—especially in the Swan after such a significant load.

Yesterday, Cam, Mark, and I returned to Kimmerly Basin. On 2/21, we collapsed the snowpack with every other step and remotely triggered a very large slide over 1,500’ wide. That day, we felt certain a human would trigger a slide if they got anywhere near a steep slope.

This time, adjacent terrain showed no obvious signs of instability, yet snow pits revealed a structure as poor and consequential as ever. We judged the likelihood of triggering an avalanche had dropped to possible, but our travel plan didn’t change a lick. We avoided even the most benign-looking slope near the ridgeline.

Structure trumps results, and the structure is bad. Stay disciplined, and find safe, good snow in low-angle terrain without any steep slopes overhead.

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