Avalanche forecast

Gunnison

Crested Butte Avalanche Center
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Avalanche danger

Sun
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

An AVALANCHE WARNING is in effect.  Heavy snowfall and wind loading are overloading weak layers in the bottom of the snowpack, creating very dangerous avalanche conditions.  Avoid traveling on or beneath avalanche terrain this weekend.  It will be easy to trigger a deadly avalanche near steep terrain - even from below the slope.  The danger will continue to rise overnight.  Destructive avalanches are likely to release as snowfall rates increase later today and tonight.    Avalanches can run long distances and reach valley bottoms.  The danger will rise to HIGH at all elevations tonight.  

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    Persistent slab avalanches have been releasing naturally all week, and avalanche activity is expected to peak during the next 36 hours of heavy snowfall.  Don't take this problem lightly: avalanches are breaking 2 to 6+ feet thick, across entire start zones and producing destructive amounts of debris in their runouts. They can be remotely triggered from flat terrain that connects to adjacent start zones.   The only way to reliably manage this problem during prolonged and intense loading periods is avoidance.  Avoid traveling in, near, or below avalanche terrain: that means stay on slopes less than 30 degrees that don't connect to steeper terrain above.    Give runouts a wider berth than your normal routine.  Natural avalanche activity will be most common on the eastern half of the compass near and above treeline, but you can trigger an avalanche on almost any aspect and elevation.  

    The crown of a recent persistent slab avalanche on Mt. Axtell

  • Storm Slabs

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

    With a foot or more of recent snow and more on the way this afternoon, you can easily trigger avalanches in the new snow.  Slabs will be most sensitive where winds have thickened or stiffened the new snow.  Shallow instabilities in the upper snowpack can trigger much larger persistent slabs, thus, avoiding avalanche terrain is the simple solution for today.  

    2/11, A wind-loaded slab released at the top of this avalanche path, then further pulled out larger and deeper persistent slab avalanches at lower elevations.

Avalanche Discussion

Yesterday's observations of avalanche activity were limited due to poor visibility.  Forecasters in Cement Creek reported rumbling collapses and easily triggered slides breaking on depth hoar near the ground.  Snow safety teams at Irwin reported touchy storm/wind slabs developing, up to D2 in size.  Explosive work has produced large to very large slab avalanches in the past two days (D2 to D3, breaking on old layers or at the ground), both at Irwin and CBMR.   On Thursday, a handful of large to very large persistent slabs (D2 to D3) released from wind loading (example A, example B, example C).   This is all just a week after one of the most astounding persistent slab cycles that I can recall (See this video).  We have been in a prolonged wind loading pattern all week, with storms on Tuesday and again on Friday adding fuel to wind transport.  This video captures the dramatic wind loading yesterday at high elevations.  Storm totals since Friday morning are 8" to 15" (.6 to 1.4" SWE).    Winds are forecasted to trend down through the day while heavy snowfall ramps up this afternoon.   Natural activity will likely resume this afternoon and surge overnight, as more snow accumulates and snowfall rates intensify into the evening hours.

Today's HIGH danger is a different flavor than the cycles we had earlier this season.  With weak layers now buried up to 4 or 5 feet deep in favored parts of the forecast area, you may not experience dramatic signs of instability like you did in December.  But these layers are still lurking and are now buckling under the stress of a prolonged loading period. Avalanche activity in the past two weeks is clear evidence that our persistent slabs are unable to handle loading events like the one we are in now. See the media gallery below for examples.   So although you may not see widespread signs of instability underfoot, you can count on very large avalanches releasing over the next 36 hours.    The evidence may not present itself until the storm clears and visibility improves.  

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