Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

More remote triggered avalanches yesterday and continued reports of a collapsing snowpack highlight dangerous conditions.    On slopes that didn't avalanche during the cycle, you can trigger a dangerous slab from on or below a steep slope, especially on slopes that face west to north to southeast.   Conservative terrain choices are the most reliable way to manage this tricky snowpack right now.  

Avalanche problems

  • Loose Wet

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

    Warming temperatures and sunshine could trigger small wet loose avalanches on steep, sunbaked slopes today.  The problem will be obvious if it develops: you'll see rollerballs, pinwheels, or small sluffs starting to shed from very steep terrain and from below rock outcrops.  Stay wary below steep gullies or in consequential terrain if you feel the snow surface getting sticky or gloppy.  There is isolated potential for a small wet loose avalanche to trigger a larger persistent slab where the problems overlap.

    This wet loose avalanche ran yesterday on a hot, sunbaked slope of Mt. Crested Butte.  It wasn't large enough to bury you, but it could ruin your day if it pushed you into trees or over cliffs.

  • Persistent Slabs

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

    You can easily trigger slabs 2 to 3 feet thick that fail on fragile facets and faceted crusts below the recent storm snow.  Avalanches can be remotely triggered from below steep slopes and they can propagate surprisingly wide distances.  On slopes that didn't avalanche during the cycle,  slabs are likely to be triggered near and below treeline on the aspects highlighted in the distribution rose.  The same problem is possible above treeline.   To avoid an encounter with a large avalanche, choose slopes that are consistently less than about 30 to 35 degrees that don't connect to steeper terrain above you.

    This photo from Cement Creek illustrates how persistent slabs can be triggered from a long ways away from the start zone.  The avalanche was remotely triggered by a snowmobile on 2/27.

Avalanche Discussion

The snowpack is still talking loud and clear.  In Cement Creek yesterday, I triggered numerous shooting cracks and remotely triggered a decent-sized persistent slab.  In West Brush Creek, an observer reported a "noisy" snowpack and we spotted a pair of large persistent slabs that may have run as recently as yesterday.  In the most snow favored part of the forecast area, an observer reported less feedback but unstable pit results. That's on the heels of a scary avalanche triggered in the same vicinity on Saturday.  The snowpack has been producing the most obvious signs of instability near and below treeline in the past few days.  That's the terrain where our treacherous facet layer is largest and most widespread.  Above treeline, winds damaged, stiffened, or eroded that layer on many slopes. Our targeted fieldwork the past few days supports the notion that slabs are bonding better to these old wind hardened surfaces, and that instabilities aren't as common at higher elevations.  We're lowering the danger to Moderate above treeline in the Southeast Mountains first, where slabs are a bit smaller than their high elevation counterparts in the Northwest Mountains.  The gradual downtrend in danger will continue through the week as slopes slowly adjust.   It's important to recognize that the consequences of triggering an avalanche remain the same, even as the likelihood decreases.  Slabs are generally breaking 2 to 3 feet thick in the Northwest Mountains and 1 to 2 feet thick in the Southeast Mountains, with a few thicker outliers in the most drifted terrain.  

Yesterday's above freezing temperatures and sunshine spurred a number of small point release wet loose avalanches from steep, rocky terrain.  With warmer temperatures on tap for today, you can expect more of the same.  Wet loose sluffs should remain mostly small today, but in sustained steep terrain, they could gain enough mass to inflict some serious harm.  There is also some concern for moving sluffs or surface warming to trigger a larger natural persistent slab where the problems overlap. 

Regions covered