Southeast Mountains

Continued reports of rumbling collapses and a steady string of large, remotely triggered avalanches highlight our tricky and dangerous snowpack.  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 a few days ago.   Though signs of instability are decreasing, our fragile weak layers are still struggling underneath slabs that are several feet thick or more, on all aspects and elevations.  You are most likely to trigger an avalanche in terrain where slabs are thinner from wind effects or in areas less favored by recent storms. Bring a conservative mindset into the backcountry.  

The steady string of rumbling collapses and shooting cracks continues, both locally and at a statewide scale, in an unusually prolonged tail of post-storm instabilities. Yesterday was the first day in almost 10 days without a large remotely triggered or natural avalanche in the Elk Mountains, and that's probably more a result of the weekend crowd returning to work.  Yesterday's forecast discussion described in detail why we are in this tricky situation: in short, a large loading event on a widespread and unusually fragile persistent weak layer.  

A few local patterns have emerged in the past few days.  In our deeper zone (Northwest Mountains), signs of instability and triggered avalanches have been most common in seasonally wind-eroded terrain, where recently formed slab depths are more variable in thickness and January weak layers are most fragile.   In some cases, these shallower trouble zones are fairly easy to recognize, such as these avalanches that appear to be remotely triggered over the weekend on the windward side of Elkton Knob.  However, this forecaster video from east-facing terrain near Purple Palace yesterday demonstrates how shallow areas aren't always easy to recognize.  If you have an intimate understanding of how wind effects and snow depths interact with your terrain of choice, there are options to ride with a lower risk of triggering an avalanche by traveling where the snowpack is consistently deeper than about 150 cm.  A more trustworthy strategy is riding on terrain where the problem has clearly avalanched away recently, identified by partially filled-in crowns and debris on the uphill sides of trees.  Lower slope angles remain the silver bullet without uncertainty or guesswork, and the low angle is riding great right now. 

In the shallower parts of the Southeast Mountains, constant collapsing has been the theme at lower elevations, where slabs are an ideal thickness for human triggering and the snowpack was exceptionally weak and shallow before our big storm.  This observation from Park Cone yesterday exemplifies the patterns that we've recently observed in lower Cement and lower Brush Creek areas.  Because of this higher sensitivity, we are showing a higher likelihood for persistent slabs in the Southeast Mountains.  As you gain elevation or move closer to the zone boundaries, the problem also appears to become more stubborn, and is most likely to be triggered in wind-affected terrain with variable slab thickness.  

It's important to recognize that terrain where the problem is becoming more stubborn also means that the potential size is typically larger, and potentially unsurvivable on larger terrain features.  We are starting to see some gains and weak layer strengthening in the deeper snowpacks on some slopes, but others are still very ugly.