Northwest Mountains

The snowpack is generally stable in the Northwest Mountains, thanks to an unseasonably deep snowpack and minimal snowfall in the past week to add stress.  Unfortunately, we can't completely rule out the isolated potential for triggering an avalanche from a shallow spot that breaks on weak layers near the ground.  This diminishing threat is most likely to occur on a high elevation slope on the north half of the compass where winds have left slabs of variable thickness.  You can give yourself an extra margin of safety by riding where the snowpack is deep and uniform.  Continue to travel one at a time in avalanche terrain and regroup in safe zones that are appropriate for very large avalanches. 

The snowpack has been atypically quiet for January thanks to the walloping that we got in December.  The extensive natural cycle of very large avalanches breaking at the ground culminated on New Year's Eve.  The last human-triggered avalanche breaking on deep weak layers in our forecast area was December 25th, and we've only seen a handful of explosive triggered avalanches this month; the most recent was about a week ago.  We are now reaping the benefits of the tremendous amount of snow that fell in December, which made the snowpack unusually deep and difficult to impact weak layers near the ground.   The lack of loading in the past week has given the snowpack a chance to adjust and has further reduced the threat of a weak layer failing if you do manage to impact it from a shallow spot.  In short, it is very difficult to trigger an avalanche right now.   We've also seen the size trend down gradually in the past two weeks because there's little snow available for entrainment in avalanche tracks now, and because we expect any slab avalanches to break on shallower slopes or more confined features than earlier in the month.  The consequences are still very serious though; we're still talking about the entire season's snowpack.  

We are dropping the danger to LOW in the Northwest Mountains first, where the snowpack is deepest and strongest, and where we have the highest confidence that avalanche conditions are generally safe.  The Southeast Mountains will follow in the next couple of days unless evidence suggests otherwise. We have lower confidence in the Southeast Mountains because the snowpack is thinner and basal weak layers are a bit more fragile.   Across our forecast area, there are fewer worrisome slopes with each day of dry weather, but the slopes that give us pause retain the same characteristics:  very steep, unsupported, rocky terrain or terrain with variable slab depths because of winds.  Slopes where the snowpack transitions from thin to thick should cause caution, such as this northwest-facing slope that was remotely triggered a few days ago in the Northern San Juans.  All of these concerns are focused on the northern half of the compass, where the foundation to the snowpack was weak and faceted before our December storm cycles.  

Several observers yesterday in the Ruby Range noted intermittent periods of wind drifting caused by northwest winds and a few inches of fresh snow.  Stay alert for small, isolated wind slabs in the alpine, and be prepared to manage your sluffs on shady, sheltered slopes if you are riding in high consequence terrain.