Northwest Mountains

Below-average snowfall and dry weather have combined to create generally safe avalanche conditions. The best skiing and riding can be found on northerly-facing slopes that are sheltered from previous winds. In those same areas, you may encounter small loose dry avalanches on steep slopes. At higher elevations, previous northerly winds have left hard slabs on the lee sides of terrain features. The last reported slab avalanche occurred on 12/27. You can reduce your chance of triggering a slab avalanche by avoiding terrain features that look smooth, hard, and rounded from previous wind loading.

Check out the weekly summary for a more in-depth read on recent events. 

The Gunnison River Basin snowpack is currently flatlined at 72% of the median. The last notable weather was a wind event that occurred on 12/25 and 12/26. Those winds produced many wind slab avalanches and some persistent slab avalanches. These avalanche problems have since quieted down again with the last slab avalanche reported on 12/27. Those lingering hard slabs have become stubborn to unreactive to triggering. We have held MODRATE avalanche danger for the longest in the SE Mountains as those hard slabs had more commonly formed above notable weak layers than in the NW Mountains. These hard slabs will be with us until it snows again, though the areas where you could still trigger them will continue to grow more and more isolated. Such as an area where one of those hard slabs is hanging out on a steep unsupported slope. In the meantime, snow surfaces will continue to facet and weaken. This process will slowly add more loose snow available for loose snow avalanches in steep terrain. 

Following the brutal wind event at the start of the week, we can break down the travel advice into two categories: wind-sheltered terrain and wind-exposed terrain.

Wind-sheltered terrain: Avalanche hazards are small and easy to manage.  The snow surface is soft, and growing weaker each day.  On the north half of the compass, you'll be able to trigger loose dry avalanches on slopes steeper than 35 to 40 degrees.  Some slopes may be weak enough now that sluffs will start to gouge deeper and entrain more snow than expected.  This observation from Snodgrass sums it up.  

Wind-exposed terrain: The potential avalanche hazards are larger.  The snow surfaces are firm and variable.   Many slopes were wind-eroded and offer safer options: look for wavey, heavily textured snow call sastrugi to identify those slopes.  Concave and leeward catchments from northerly winds caught the drifting snow and formed dense slabs. Some of those slabs formed over weak layers or added stress to weak layers deeper in the snowpack.  We have more evidence of these issues in the Southeast Mountains, including frequent collapses and notable avalanche activity in Upper Cement Creek, explosive results Thursday at CBMR, and a skier caught and carried on Mt. Emmons.  The Northwest Mountains experienced the same wind-loading event, though the recently buried weak layers and over-stressed structures appear to be less common on a regional scale. This Ruby Range observation (click through the media gallery) from before the wind event demonstrates several layers and structures of concern on what are now leeward aspects from northerly winds.  You might find unstable structures on slopes that were shallow and weak all season and recently experienced significant loading, like this large avalanche on the west face of Gothic.   The easiest way to manage the problem reliably in both forecast zones is to simply stay off of the slopes with obvious wind loading from the recent wind event. 

The next CBAC outreach event is today, at the Washington Gulch Trailhead. The CBAC will be available to chat about conditions and backcountry resources.