Northwest Mountains

A few more large naturals that ran in the Elk Mountains on Monday and Tuesday exemplify how our dangerous buried weak layers are still struggling under the weight of the recent storm, which formed slabs several feet thick or more.  You can trigger large avalanches with little or no warning signs, such as this remotely triggered avalanche that snapped trees on Sunday, or this destructive avalanche on Mt. Baldy last Friday.   Poor snowpack structures exist at all elevations and aspects. In the Northwest Mountains, you are most likely to trigger an avalanche where the snowpack is thinner in wind-affected terrain, especially on windward aspects. 

Changes to the snowpack have been slow and gradual this week. If you're just catching up on conditions, click back through our forecast archives to learn more about why conditions are still dangerous, and some local patterns on which types of terrain have been most sensitive to human triggers.  Those discussions are still relevant.

The biggest news today is that a few more large natural avalanches appear to have run the Elk Mountains in the past 24 to 48 hours: a D2.5 near Aspen Highlands, and a couple of D2s near Marble.  Natural avalanches during quiet weather patterns like we are in right now are unusual, and this further demonstrates the challenging snowpack we are dealing with in our region.    Sadly, Colorado's first avalanche fatality of the season occurred near Ophir on Monday.  The entire state, and for that matter, most of the Intermountain West from Utah to Wyoming to Idaho is dealing with the same setup: fragile December drought layers now buried by large January slabs.  

Today, we lowered the danger below treeline to Moderate in the Northwest Mountains, our first dose of yellow since the storm cycle first escalated on January 10th.  Evidence for the decrease is fewer and smaller avalanches reported in the past week from below 11,000' in our deeper zone, and observed downtrends in signs of instability and test results.  Extensive previous natural activity and more uniform slab characteristics on most below treeline slopes are likely helping the situation.  However, on specific terrain features, you can still trigger a dangerous avalanche, similar to the avalanche fatality near Ophir that occurred below treeline.  This observation from the Upper Slate illustrates some below treeline features that are most problematic.  Near and above treeline slopes in the Northwest Mountains may not be far behind with the danger drop, but the larger potential sizes, higher degree of slab variability from wind effects, and recent naturals at higher elevations are dictating the travel advice and danger rating right now.  With additional snow and wind-loading starting Thursday afternoon, we don't expect to see any changes in the danger until after this next storm pushes through.  

The danger is still Considerable at all elevations in the Southeast Mountains.  Below treeline, the shallower slabs are ripe for human triggering, especially in the shallowest parts of the zone.  Yesterday, we traveled near Cement Mountain and observed widespread collapses and shooting cracks up to our turnaround at 11,000', a truly miserable snowpack that made it easy to want to stay away from steep slopes.