Avalanche forecast

Gunnison

Crested Butte Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

It's another great day to tackle spring objectives but plan for increasing wet avalanche hazards.  The avalanche danger is Low this morning rising to Moderate as the day heats up.  Choose less consequential terrain once the snow surface starts to rollerball, pinwheel, or thaws to more than ankle-deep wet snow.   Persistent slab avalanche concerns have become increasingly rare but remain an isolated threat on high, northerly aspects, especially on rocky or shallow slopes.   

Avalanche problems

  • Loose Wet

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

    Watch for shallow sluffs in the upper snowpack as it gets wet from solar radiation and warming temperatures.  Instabilities will be easy to recognize: look for rollerballs, pinwheels, or sluffing from very steep slopes.  Use sluff management techniques or move to lower slope angles to manage the problem if it develops.  Even though most wet avalanches today are expected to be relatively small, they can pack enough punch to carry you down a gulley, over a cliff, or into trees. In isolated areas, a wet slide might gather enough volume to be large in size.  You can avoid the issue by moving to colder aspects where the snow surface is still frozen or just starting to thaw.  

    This is one of the larger wet loose avalanches observed this week. Notice how the wet snow is sliding on a hard crust buried a few inches deep, and how they can accumulate mass in bigger terrain. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1.5–2.5

    High-consequence persistent slab avalanches have become isolated and difficult to trigger.  The most problematic terrain is on high elevation, northerly aspects in areas with relatively shallow snowpacks (<175 cm).  Old facet layers are weaker and easier to impact in steep rocky slopes with variable snow depths.   This video highlights this type of terrain.  You can reliably avoid the problem on the southern half of the compass, where the snowpack has transitioned to more of a springlike structure.  

    Persistent slab avalanche crowns spanning steep, rocky terrain on a north facing, alpine slope. This avalanche ran sometime during the late March storm cycle and wind-loading event.  

Avalanche Discussion

This week's gradual warming trend wetting the modest amounts of fresh and windblown snow from last weekend has limited wet avalanche activity to a few small natural and human-triggered wet loose slides.  With the warmup escalating today, we're expecting wet instabilities to become a bit more common, and they may grow larger on a few slopes.  I expect the most active slopes today will be on the southern half of the compass at higher elevations or on more northerly aspects at mid to low elevations, where last weekend's storm snow is still transitioning.  Like earlier this week, these instabilities should be shallow and relatively small.  However, there is isolated potential for a shallow sluff to run down steep terrain towards a late-day saturated snowpack at lower elevations and grow larger.   Early travel and monitoring for the obvious surface clues signaling deteriorating stability are your best tools.  Look for rollerballs, pinwheels, or wet sluffing to develop first on northeast and east aspects later this morning, then south by midday, then west-facing terrain this afternoon. 

Persistent slab concerns are becoming increasingly rare with each passing day of dry weather.  Given the poor structures that have plagued us all winter, we can't rule out the isolated potential for triggering a larger slab avalanche where the snowpack has remained dry on high, northerly aspects.  In our forecast area, the last persistent slab avalanche was accidentally triggered on April 3rd, and just outside of our forecast area, an accidentally triggered slab occurred on April 10th near Star Peak.  This was likely a wind slab that formed last weekend and hadn't healed up yet. This observation from Purple Ridge on Monday highlights how wind slabs that formed on higher, colder aspects may persist longer on a few features.  At this point, those concerns are now managed and characterized as persistent slabs.  

Tonight, mild temperatures and increasing cloud cover will make for a weaker refreeze than we have seen all week.  Plan for an earlier start on Saturday to stay ahead of another day with increasing wet avalanche concerns.  A hot day today followed by a mediocre refreeze tonight increases our concerns for larger wet avalanches this weekend because meltwater will be breaking down the solid crusts from last week's warmup and moving deeper into the snowpack.  

Regions covered