Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
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Avalanche danger

Sat
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The bottom line is simple today. Avalanche conditions are very dangerous. Travel in avalanche terrain is not recommended. There were many human-triggered and natural avalanches reported yesterday. Overnight another couple feet of snow has accumulated, making the snowpack even more unstable. 

Avalanche problems

  • Persistent Slabs

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

    2 to 4 foot slabs have formed over a very weak foundation. That weak foundation consists of anywhere there was old snow on the group to start the week. These avalanches could still run naturally today and will be very sensitive to human triggers. You can also trigger this avalanche problem from low angled slopes connected to steeper slopes, and release an avalanche that propagates widely through the terrain connecting multiple avalanche paths. 

    This was a remotely triggered avalanche on 12/9, that propagated widely through the terrain and would easily have buried a person. 

  • Storm Slabs

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

    The current storm is creating soft slabs, that can release within the recent storm snow, even on slopes that were bare ground a week ago. These 1 to 3 foot slabs will further grow in size and sensitivity near wind-loaded terrain features. The wind direction is forecasted to shift from SW to NW or even N today, and begin actively wind-loading the southern half of the compass this afternoon. 

Avalanche Discussion

Accumulated snowfall numbers are absolutely impressive across the entire forecast area. In the NW Mountains, Schofield Pass has accumulated upwards of 3.5" SWE or around 4 feet of snow over the last 48 hours. In the SE Mountains, the Mt Crested Butte Snotel has accumulated 2" SWE or 2 to 3 feet of snow in the last 48 hours. This is a significant loading event for any storm throughout the winter. The difference with this storm is, the total volume of the snowpack, and what this snow is accumulating on. 

Regarding the volume of the snowpack: A natural avalanche cycle occurred overnight and will continue into Friday. However, the current volume of the snowpack should not lead to a valley-crushing natural avalanche event like we could see if this storm happened later in the winter. Instead, there will be many, many, large natural avalanches that will run through 2 elevations bans, but few are expected to run through all 3 elevation bans. Does this matter? Not really. It's still very dangerous out there and this is just some context on how this HIGH danger event compares to other mid-winter HIGH danger events. 

Regarding what this snow is accumulating on: We've had an extremely dry start to the winter. That dry period left any snow that survived, as weak as it can get. Creating a very weak foundation for the current storm to build on. Those extended dry periods also left lots of bare ground for the snowpack to build on. Head to the observations tap and dig back to understand what slopes had old snow, and what slopes didn't have old snow if you want to dig deeper. Slopes that didn't have old snow earlier this week may be manageable for experienced backcountry travelers.

The avalanche danger is forecasted to drop on Saturday with the end of the loading period. However dangerous avalanche conditions will persist through the weekend. 

Regions covered