Avalanche forecast

Southeast Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche danger is currently driven by the previous wind-loading that has occurred during the last week, and the low probability but high consequence of triggering a large persistent slab avalanche. The most suspect areas are where these avalanche problems overlap at near and above treeline elevations. There is a slightly reduced risk of triggering an avalanche in wind-sheltered areas. Make a plan with your group on how to either manage or avoid these avalanche problems. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Over the past few weeks, we have observed an infrequent but continuous pattern of large avalanches or collapses failing on weak, faceted layers deeper in the snowpack.  Such as this remotely triggered avalanche that occurred near the Friends Hut on Wednesday. Persistent slab activity has been most problematic on wind-loaded terrain this month, though issues are developing in some areas below treeline.  Carefully assess the snowpack structure and give yourself a margin for error in handling this problem because there is a high degree of variability across the region and on different aspects.  Some recent examples of persistent slab activity include this very large skier-triggered avalanche near Ashcroft, naturals on Express Creek and Carbonate Hill, and a remotely triggered avalanche on Mt. Emmons. 

    This large avalanche on Whetstone was reportedly human triggered from above. It looks like it gouged to the ground in a shallow start zone.

  • Wind Slabs

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

    The wind has been mostly calm to light for greater than 24hr now. While in the alpine there have still been wind gusts into the 20's from the west and north. You could find an isolated wind slab that has freshly formed and is more reactive, but in the big picture, this avalanche problem is stubborn and more difficult to trigger. Earlier this week we had an extreme wind event from the southwest, with continued strong winds into Wednesday. Those old slabs will still require some consideration near ridgelines and cross-loaded terrain features. The recent avalanche activity from this last week is well documented in the observations tab. 

    This recent avalanche has a combination of terrain characteristics that you would still want to avoid. The slope is wind-loaded, steep, and unsupported by the rollover below the crown.

Avalanche Discussion

West Elk Air has come through many times now to help the forecast team document avalanche activity after notable weather events. Big thanks to them, as it is really helpful for us all to have this data. On a daily basis, public observers continue to send in detailed observations while we also have local avalanche forecasters in the air and on the ground. We sure have something special going on in this valley. 

 

So what did we learn from all the avalanche data we received yesterday? This past week was characterized by an extreme wind event from the southwest, combined with 1 to 2 feet of snow across the forecast area. We expected some amount of natural avalanche activity with avalanches releasing in the new snow and in some areas breaking into persistent weak layers. The avalanche size was in the D1 to D2 range and not large enough or widespread enough to have pushed us into HIGH avalanche danger or an avalanche warning. 

In the NW Mountains, some cornices fell, and both wind slab and storm slab avalanches released, up to D2 in size. The persistent slab avalanche problem was listed at unlikely, and we have only observed avalanches stepping down into deeper weak layers in one location so far. This was on a steep slope that held a below-average snowpack height due to past avalanche activity. Zach had previously documented the weak snow in this area back in mid-February.

In the SE Mountains, the avalanche activity was mostly the same with cornices releasing and both wind slab and storm slab avalanches to D2 in size. However, there were more avalanches that stepped down into persistent weak layers. The persistent slab avalanche problem has been in the "possible" category for some time now, and that is a step higher on that likelihood scale than the NW Mountain forecast. The most common areas where persistent slab avalanches were observed, were below cornices and in steep rocky terrain. 

All the recent avalanche data can be viewed in the observations tab, avalanche table and the avalanche rose. 

 

Looking ahead to the weekend, the wind will continue to drive the avalanche danger. Late Saturday afternoon and into Sunday it is looking like we'll have another extreme wind event. 

 

Regions covered