Avalanche forecast

Swan Range

Flathead Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Out of date — this forecast expired 6 months ago. You’re viewing past conditions, not the current bulletin.

Highlights

A wallop of a storm landing on a weak snowpack makes human-triggered avalanches likely today. Slides may break within the new snow or step down to buried weak layers 1-5 feet deep, producing large and destructive avalanches. Stick to simple terrain and avoid steep slopes and their runouts, big or small.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    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. While these slides were becoming slightly harder to trigger before the storm, a massive load of 3 inches of Snow Water Equivalent just blanketed the Swan Range. 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. 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

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    1-2 feet of heavy, dense snow fell in the past 48 hours, and the new and wind-drifted snow will likely be sensitive to your weight today. Avalanches will grow deeper and more dangerous with elevation, especially in wind-loaded start zones near ridgelines and saddles. On shaded slopes, avalanches in the new snow could step down to a buried weak layer, producing a much larger slide.

    If you head to southwest or west-facing slopes to avoid the persistent slab problem, keep new snow avalanches on your radar. Look for hard-over-soft snow and shooting cracks emanating out from your feet or machine, and default to lower-angle terrain if you see signs of instability.

    (4/7/2024)

    This is a soft slab avalanche that failed in the storm snow in a previous season. This is one type of slide that riders could trigger today in areas favored by recent snowfall.

    Photo: Jeff Metsky

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.

Regions covered