Avalanche forecast

Northwest Mountains

Crested Butte Avalanche Center
View on map

Avalanche danger

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Out of date — this forecast expired 2 years ago.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

Highlights

Small wind slabs have formed on the lee sides of terrain features, thanks to an easterly to southeasterly wind direction. While in wind-sheltered areas you can encounter dry loose avalanches on steep northerly-facing slopes. Both of these avalanche problems will require some assessment, and management if you want to ride in steep avalanche terrain. There continue to be lingering concerns for triggered avalanches releasing deeper in the snowpack in areas where the total snowpack height is below average and variable in depth, like this avalanche on Mt Baldy.

Avalanche problems

  • Wind Slabs

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

    Over the last 24 hours, the wind direction has been out of the east to southeast and those winds have formed small wind slabs on the lee sides of terrain features. Make a plan to manage this avalanche problem before committing to bigger avalanche terrain. Pillowy-looking snow deposits will help you clue into the local wind-loading patterns in your area and small test slopes can help refine the potential avalanche size. Earlier this week, we had wind loading occurring from westerly and northerly winds, so be prepared for more isolated wind slabs around the rest of the compass. 

    A small wind slab on the lee side of a cross-loaded terrain feater. Mt Axtell, 3/14.

  • Persistent Slabs

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

    In the Northwest Mountains, high-consequence slabs breaking on older weak layers have become isolated and difficult to trigger. Persistent slabs are most likely to be triggered from a shallow, previously wind-eroded slope where the total snowpack height is below average or shallow, and from random cornice falls. Persistent slab avalanches can be remotely triggered from low-angle terrain and break deeper and wider than you might expect.  The most problematic structures are on shallower slopes on the north half of the compass and a few high, southerly aspects.  Mid to low-elevation, southerly aspects have the most trustworthy snowpack.  Slope angles consistently less than 30 degrees are a reliable way to avoid the problem when in doubt.  

    The crown of a very large persistent slab remotely triggered by snowmobiles on March 8.  This slope is west facing and eroded by seasonal winds, making for a shallower and more problematic snowpack than other slopes. 

Avalanche Discussion

Remote weather stations such as Scarps Ridge and Cinimmion Mountain are not capturing the recent winds very well. The weather station at 11,000ft on CBMR is highlighting the recent easterly winds the best, with average wind speeds in the teens to twenties and gusts in the twenties to thirties. Light snow accumulations through the week have kept small to moderate amounts of snow available for transport into our current wind slab avalanche problem. We rarely see easterly winds, so remember these wind-loading patterns are not what we typically encounter. Wind slabs are currently driving the avalanche danger rating in the NW Mountains while the persistent slab avalanche problem continues to drive the danger in the SE Mountains. 

The freezing level looks like it will climb to around 10,000ft today. If the cloud cover is thin enough, we may get some greenhouse weather and moist snow surfaces on southerly-facing slopes. 

The snowfall over the past few days is gradually adding small amounts of stress to our persistent slab problem. The pattern of triggered and natural persistent slab avalanches over the past 2 weeks clearly points to areas with shallower snowpacks being the most problematic. Most of the avalanche activity has been in the shallower part of our forecast area (the Southeast Mountains), and the few persistent slabs in the deeper zone occurred on windward slopes or on slopes that have repeatedly avalanche this season keeping the snow depth unusually shallow. This avalanche problem has the lowest likelihood of triggering in consistently deep snowpacks (>200cm). This video of a recent persistent slab on Gothic shows how shallow spots and variable snow depths are more common in wind-affected, alpine terrain.

CBAC Event:  Don't forget the 50th Al Johnson Race is this Sunday, March 17th.  Registration and information can be found at cbavalanchecenter.org.  All proceeds to benefit the CBAC.

Regions covered