Lawinenlagebericht

Swan Range

Flathead Avalanche Center
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Lawinengefahr

Wed
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 7 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Recent avalanche activity and audible collapses indicate that it is possible to trigger an avalanche that fails a foot deep on buried weak layers. Slabs will be thicker and more unpredictable on wind-loaded slopes. Safer options for riding are on slopes sheltered from southwest winds or on low-angle terrain.

Lawinenprobleme

  • Persistent Slabs

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

    A recently buried weak layer is proving untrustworthy. Reports of remotely triggered avalanches, shooting cracks, and audible collapses continue to trickle in each day. Expect to encounter similar signs in areas where 6 or more inches of recent snow fell, or where winds drifted snow into thicker slabs.

    You can identify the weak layer by visualizing a grey strip in the upper snowpack, or by locating the uppermost crust. It will vary from place to place. Wind-loaded areas will be the most dangerous, since that is where slabs are thicker and harder. Seek out terrain sheltered from west and southwest winds. If you observe signs of unstable snow (shooting cracks, whumpfs, or triggered avalanches), resort to lower-angle slopes for a safe riding experience.

    (1/31/2026)

    Riders traverse over hard slab debris from a remotely-triggered avalanche. We assume this slide failed on a layer of surface hoar.

Avalanche Discussion

The hot topic right now is a recently buried weak layer. The type of weak layer varies across the forecast zone. Beneath about a foot of snow, you may find a grey stripe (indicating surface hoar), or a weak layer of near-surface facets. In most cases, both of these weak layers sit on or near crusts. Hand pits are proving productive for locating this interface because the weak layer is buried less than a foot down in most places.

To be transparent, assigning a danger rating to today’s persistent slab avalanche problem is challenging. Remember, the avalanche danger rating scale is exponential, not linear. Today is a day I’d call “spicy moderate.” Here is why.

Recent avalanche activity is mostly small (D1-D1.5), with a couple of large (D2s) in wind-loaded terrain. Whumpfs and shooting cracks suggest slabs are still ripe for human-triggering. In wind-sheltered terrain, you’ll be mostly dealing with a 6 to 8-inch soft slab, which can be manageable for a seasoned rider. On the flip side, heavily wind-loaded terrain along ridge crests in the alpine will be sporting a dense, hard slab that deserves a wide margin. I suggest avoiding that terrain altogether. So, although signs of instability do exist, the travel advice (heightened avalanche conditions on specific terrain features) and avalanche size (Mostly D1s with some D2s) fall more into the moderate range. I’ll emphasize again, we are on the high end of moderate (see image below). 

Today’s weather forecast of partly cloudy skies and mild temperatures should have little effect on avalanche conditions. The caveat is if the sun makes an appearance this afternoon. If that occurs, expect to see rollerballs and some small wet loose avalanches from steep, solar-facing slopes.

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