Lawinenlagebericht

Gunnison

Crested Butte Avalanche Center
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Lawinengefahr

Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

All of the slab activity in the past week has been in wind-affected terrain. Seek out softer, wind-protected snow in sheltered terrain for better riding conditions and a minor chance of triggering a slab avalanche.  You'll have to manage for gouging point-release avalanches on slopes that roll steeply to around 40°, and they might grow larger than expected as they entrain the weak snowpack.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    Slabs up to several feet thick are becoming increasingly isolated and difficult to trigger but remain a concern on some steep slopes facing west, north, east, or on wind-loaded southerly slopes.  You are unlikely to see signs of instability before triggering an avalanche that breaks on old weak layers.  Previously wind drifted terrain appears to be the most problematic, especially where slabs are thin near their margins, convexities, or rocky areas. You can reliably avoid the problem on slope angles less than 30 degrees without steeper slopes above you, and most wind-protected terrain lacks the problem.  

    This persistent slab in the Anthracites appears to be triggered by a rider on 1/18/2025. Note how the slab released on the lee side of a tree fence and convex roller that had been previously cross-loaded.

  • Loose Dry

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–1.5

    You can easily trigger gouging  "facet sluffs" on some very steep (~40° ) slopes that are protected from the sun and wind.  You're most likely to encounter the problem in start zones that have avalanched multiple times this season and have an unusually shallow and weak snowpack (<50 cm).  These avalanches release predictably and start small, but can grow to harmful sizes in long relief or if they push you into trees or gullies.  Use defensive or off-fall-line riding techniques to manage the problem, or move to lower slope angles to avoid the problem.  

    These paths in Climax Chutes each has a small point release that produced a significant amount of debris in this long, steep, gullied terrain.  

Avalanche Discussion

The steady stream of sizeable human-triggered slabs in late December and early January has slowed to a trickle since January 8th.  Our public observations page was quiet over the weekend, suggesting people enjoyed our current period of lower likelihood slab instabilities without encountering glaring issues. I suspect part of the reason is that our slabs are self-policing right now: the most worrisome terrain for triggering a slab avalanche has stiffer, more wind-affected snow, which isn't all that attractive to ride.  Our forecast team targeting slab concerns this weekend remotely triggered a drifted slab on a small slope and found several propagating test results on buried weak layers  (video from Mt. Emmons, video from Schuylkill Ridge). These results highlight the continued potential for human triggering, which likely requires hitting the wrong spot (probably a thin area) on the wrong slope (probably a previously drifted slope where slabs are stiffer).  

We've also been targeting our dry loose (or "facet sluff") problem this week, and the current setup looks like a good candidate for catching someone off guard.  Most lower-angle terrain has a deeper, stronger snowpack that doesn't feel sluffy or rotten.  It's not until you drop into a steep start zone, one that has avalanched a couple of times this season, that you encounter a thin and cohesionless snowpack.  Even then, there is sometimes enough wind effect on the snow surface to keep the issue at bay (Ex. A, B).  However, the evidence is clear that once you find that wind-protected snow surface and get the snow moving, it will entrain a significant volume and can pack a serious punch, easily large enough to drag you through trees (See recent avalanches here, or a video of the problems here and here).  

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