Avalanche forecast

Gunnison

Crested Butte Avalanche Center
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Avalanche danger

Sun
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Several parties unintentionally triggered surprisingly wide or dense wind slabs at upper elevations yesterday (Example A, Example B).   Be cautious of recently drifted terrain features where the snow surface looks or feels stiffened by wind.  Stay alert for shallow sluffs in very steep terrain where the snow surface is soft.     Small avalanches can be harmful if they push you into gullies, cliffs, or trees.  

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Recent northwestly winds have formed thin slabs of drifted snow in leeward and crossloaded features.  Several wind slabs were unintentionally triggered yesterday at higher elevations.   These slabs are dense enough to knock you off your feet or break around you, especially where drifts are dense and firm.  Ride around obvious drifts and avoid consequential terrain where the snow surface feels stiffer and thicker.  Cracking or collapsing are clear warning signs to choose more wind-protected or mellower terrain.  

    1/27:  A rider triggered wind slab near Mt. Owen.

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    Dry loose avalanches (sluffs) are most problematic on the north half of the compass, especially in wind-sheltered terrain.   Where the upper snowpack is weak and cohesionless, you can easily can easily trigger small sluffs on slopes steeper than about 38 degrees.  Ski cuts, moving across the fall-line while descending, or choosing lower-angled slopes are effective techniques to manage this problem.  Use extra caution above terrain traps such as gullies or cliffs or in sustained steep terrain where sluffs can gather volume.

    A great example of sluff management in terrain where sluffs could be more problematic because they get funneled down a gulley.  

Avalanche Discussion

With fantastic mountain weather and a relatively deep and strong snowpack lacking deep instabilities, it's a great weekend for traveling in the mountains.  With incremental bouts of snow and periods of wind transport late this week, the avalanche danger has been toeing the line between LOW and MODERATE, which is a fine line for us to hone in on.  Perhaps a day late, or perhaps we're overcorrecting, but we're lifting the danger to MODERATE to account for heightened concerns for wind slab avalanches at higher elevations.   Here's the scoop.

A period of wind drifting late Thursday formed a round of thin wind slabs over the weak facet layers that have been forming all month.  The uptick in unintentionally triggered wind slabs yesterday suggests that wind drifting was more extensive than we expected.  A couple of the slabs broke wider and stiffer than we've seen all month. One was remotely triggered and accompanied by reports of collapsing.  Check out these observations from Mt. Owen, White Rock  Mountain, and Red Lady Bowl.   Some groups found nice soft powder in the alpine as well, so it is clearly not a widespread problem.  If your travels take you to terrain where snow surface starts getting denser, thicker, or grabbier, you are entering wind slab territory.  Wind slab issues should still be small in size, but unlike all the sluffing we've seen recently, they are stiff and dense enough to break above you and around you.  The problem should slowly improve through the weekend, especially on southerly aspects after today's warmup. Thus, we are trending the danger back down to LOW for Sunday unless evidence suggests otherwise. 

We recently listed dry loose avalanches as a problem.  Small doses of snow and continued surface faceting in sheltered terrain have gradually increased the potential size of sluffs this month.  On shady aspects near and below treeline, sluffs can run further or gather a bit more volume than you might expect because of how weak the upper snowpack is.  This is especially true where the snowpack is shallow, either from previous avalanche activity or in extremely steep or rocky terrain.   All of the sluffs we have observed so far this week have been small in size (D1 or D1.5), but they are getting large enough to ruin your day if you get pushed into a terrain trap.  Sluffs are easier to manage but require your attention, never the less.  

 

Regions covered