Lawinenlagebericht

Gunnison

Crested Butte Avalanche Center
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Lawinengefahr

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

Although the danger rating is LOW, you could trigger an avalanche in isolated places.  The first potential avalanche issue can be found on upper-elevation slopes, where you encounter hard, wind-drifted slabs like this human-triggered avalanche just north of Pearl Pass on Monday.  You can reduce the chance of triggering a slab by steering around smooth, hard drifts you encounter in leeward terrain.  The second small issue today comes from warm temperatures and sunny skies.  Monitor the snow surface for warming and avoid steep slopes if you find a wet, punchy snowpack.

Lawinenprobleme

  • Persistent Slabs

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

    Slabs up to several feet thick have become isolated and difficult to trigger, but remain a concern on a few previously wind-drifted slopes.  You are unlikely to see signs of instability before triggering an avalanche that breaks on old weak layers.  The most concerning terrain features are where old, drifted 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 wind-protected terrain generally lacks the problem.  

    This slab avalanche was observed yesterday on the northern side of Mt Wetstone. It's estimated to have been triggered by wet loose avalanche releasing from the easterly slope to the right. 

Avalanche Discussion

The danger rating dropped to LOW for Thursday, but you may need to manage two types of avalanches today.  The first issue relates to a warming snowpack and the potential development of Wet Loose avalanches.  Last night, temperatures dropped below the freezing mark not long after dark at most locations and skies cleared, providing a reasonable refreeze.  Even with a refreeze overnight, warm temperatures and solar radiation may break down surface crusts on some slopes and open the possibility for Wet Loose avalanche activity.  The locations I am most suspicious of face easterly and westerly aspects protected from the wind or surrounded by rocks.  Here, you will find crusts just an inch or two thick that rest above a dry, faceted snowpack.  If those crusts fully break down from warming, you could trigger a loose avalanche in the wet snow that entrains the weaker faceted snow below.  A final consideration for Wet Loose avalanches is the light, brown dust you may encounter on some slopes.  Dust on snow often heats the snowpack faster than expected, even when the dust layer is subtle.  Expect to find a softer, wetter snowpack if you encounter a dusty surface. 

The Persistent Slab problem is unlikely due to an isolated nature across the landscape and a difficult-to-trigger sensitivity.  You can find old, hard slabs of snow below ridge tops, cross-loaded in gullies, and pressed into concave features.  They often appear smoother and feel harder than the surrounding snow.  Even though this problem is unlikely, it's not impossible.  On Monday, two slabs released on Mount Whetstone naturally, and a skier triggered a hard slab just outside the CBAC forecast boundary near Pearl Pass on a northerly slope.  You can reduce the chance of this unlikely problem by avoiding terrain features where you find old wind drifts. 

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