Avalanche forecast

Gunnison

Crested Butte Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 6 years ago.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

Highlights

A prolonged period without snowfall makes it unlikely, but not impossible, for you to trigger an avalanche.  Last week's extreme wind event formed thin, hard slabs at all elevations in isolated places.   A skier found just the right location on Monday and triggered a small slab avalanche into a higher consequence terrain trap.  Look and feel for thin, stiff slabs hiding on leeward features to avoid triggering an avalanche in isolated areas or extreme terrain.

Avalanche problems

  • Persistent Slabs

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

    The odds of triggering a persistent slab continue to decrease under our current snow drought.  On steep terrain features with previous windloading, you may be able to trigger persistent slabs up to several feet thick that fail on weak snow near the ground. Even below treeline, shallow pockets of hard slab exist in a few leeward terrain features.   Persistent slabs often surprise even the most experienced travelers because they give infrequent or irregular feedback.  To avoid this problem,  choose routes that stay off of steep terrain holding dense slabs over sugary weak layers.   You can read the snow texture and avoid terrain where the snowpack looks or feels deeper, denser, and more windloaded to help you avoid the problem.  The most concerning slopes are on northeast, east, and high southeast facing terrain.  You may be able to find isolated exceptions to the distribution rose on cross-loaded terrain features on other shady aspects.  Riding on steep terrain where the snowpack is softer and faceted throughout is the safest option.

    1.18 Small skier triggered hard slab on a cross loaded terrain feature. This avalanche ran into a higher consequence terrain trap formed by the Slate River below.

Avalanche Discussion

There are two flavors of Persistent Slab avalanche problem scattered across the landscape around Crested Butte.  The first, mentioned in the Bottom Line, are thin, hard slabs that formed from last week's extreme wind event.  You can find this structure at all elevations, but it is isolated across the landscape, tucked into nooks and crannies on leeward breaks in the terrain.  A good example can be found in this observation of a skier-triggered avalanche on Monday.  The second flavor of Persistent Slab comes from old, weak snow at the bottom of the snowpack.  The extreme wind event from last week scoured many slopes that had slabs, but you can still find terrain features at upper elevations with slab/weak layer structure.  This slab/weak layer combination fits into LOW danger because it has become unreactive.  Stability tests over the past few weeks have slowly improved to the point where propagating test results have become rare.  It is not impossible to find a very isolated place where you could pry one loose, but it has certainly become unlikely.  Check out this observation from Wednesday on Mount Baldy to see some more information about unreactive slab/weak layer structure on an east-facing slope near treeline.  To deal with both flavors of Persistent Slab consider the consequences of being caught off-guard.  Terrain traps like creek bottoms, trees, or cliffs (extreme terrain) can greatly increase the consequences of a small avalanche.  Choose terrain that doesn't magnify the consequence of a small avalanche by avoiding terrain traps.

Now for a bit of excitement.  An incoming storm will begin to impact the Crested Butte area on Friday.  Snowfall will slowly ramp up in the afternoon and certainly overnight into Saturday.  Models currently show just enough snow before sunset on Friday to warrant showing an increase in the danger rating for Friday on near and above treeline slopes.  By Saturday it is reasonable to expect that the danger rating my rise significantly due to substantial new snow and lots of weak old, snow surfaces.  Check out this video from Zach Guy for a tour around the CBAC forecast area demonstrating the weak snowpack.  By Friday morning, we will have a clearer picture regarding snowfall totals, but you should anticipate dangerous avalanche conditions to develop this weekend if the incoming storm materializes.  

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