Northwest Mountains

Dangerous Avalanche Conditions continue to prevail. Both right here in our forecast area, and across much of Colorado. Persistent weak layers buried one to several feet deep have shown minimal signs of improvement recently. The best travel advice right now remains to keep your terrain choices simple, and conservative. For aspects highlighted by the avalanche problem rose you can still have a fun time if you keep those slope angles near or below 30 degrees while keeping an eye out for overhead hazards. Many south-facing slopes lack the current avalanche problem and can be another great terrain option for skiing and riding. Just be heads up for crusty snow on southerly facing aspects this afternoon when clouds build. A small area of Southeast has been on the problem list for some time and was highlighted by yesterday's skier triggered avalanche in Red Lady Bowl. 

Mild weather yesterday, and again heading into this morning, would normally lead to a decreasing avalanche danger trend as the buried weak layers have time to adjust to their current load. However, we are still seeing very obvious signs of instability in many areas. The observations page has been stated to read like a "horror story". Take the time to read through the dozens of observations of naturals, human and remotely triggered slides, collapses, and shooting cracks. While the slides in the alpine on Richmond and Yule Pass are scary large, the dozens of smaller slides in below treeline terrain like Snodgrass or Coney's should also catch your attention. The wind loading at upper elevations has briefly ended, but our next storm is moving in tonight and arriving with more strong winds. While persistent slabs remain reactive to the weight of skiers and riders, natural avalanche activity is potentially on the horizon again for this evening and tomorrow morning. 

Below is a good section from Zach's discussion from yesterday if you would like to read into the data behind the current Avalanche Problem Distribution Rose. 

Thanks to everyone's observations from the past week, we have compiled an impressive record of avalanche activity since our fragile weak layers were buried on December 10th.  Let's dive into that data a little now, which I have included in the first image of our media gallery below.  This discussion will add more detail and insight into our current persistent slab distribution rose.   Since our snowy period began on December 10th, we've recorded 254 avalanches.  Almost half of these were from below treeline slopes, where the persistent weak layer is weakest thanks to our strong inversions in early December when it was forming.    You'll notice that all of the activity below treeline was on west through north through east aspects.  That's where there was existing faceted snow coverage prior to the storms.  Northeasterly aspects are the epicenter of activity.  That's in part, because those slopes held the weakest of the weak layers: they were the most protected from the sun and from the wind back when the weak layers were forming.  There's also a strong data bias here because our valley's geography is such that most of our avalanche terrain on shaded aspects faces northeast to east (think Snodgrass, Coneys, Schulkill Ridge, Happy Chutes, etc).  I wouldn't read into the lack of avalanche activity below treeline on northwest aspects: we simply don't have many northwest facing slopes that we can access or see easily.  At higher elevations, northwest aspects have been getting scoured by numerous northwest wind events, so finding a slope holding persistent slab structure is less common. We've kept it on the rose for simplicity's sake.  The 12/10 weak layer wasn't quite as weak above treeline, thanks to various wind effects and wind crusts capping it before burial.  While there have been fewer slides above treeline, you'll notice the destructive sizes are generally larger.  That means it may not be as easy to trigger an avalanche in the alpine, but if you do, it will be larger.  The final and most important point is the lack of avalanche activity on southerly aspects. South facing terrain was either dirt or thick crusts prior to our storms, so there aren't persistent weak layers below the recent snow.  As you wrap further away from due south, the buried crusts get thinner and more collapsible.  We've seen a few slides on SW and SE aspects above treeline which may have been from these crusts collapsing, or which may have simply been wind slabs on non-persistent weak layers.  Either way, our snowpack assessments suggest that as you move away from due south towards SE to ESE aspects or to WSW aspects, the persistent slab structure becomes evident again on steep terrain.  If you're hunting out steeper terrain on the southern quadrant of the compass, the more due south-facing, the better,  and be mindful of smaller wind slabs that formed over the weekend.