Southeast Mountains

Avalanche conditions have improved recently, but human-triggered avalanches remain a concern on most aspects and elevations.  On Friday, explosive work triggered a large avalanche at Irwin and a skier in the Marble area had a close call.  You are most likely to trigger avalanches in places where slabs become thinner such as wind-affected slopes, rocky terrain, or portions of the forecast zone that receive less snow.  You will find an increased likelihood of triggering an avalanche where the snowpack is about 3 to 4 feet deep.  You can reduce your chances of triggering an avalanche by choosing slopes with a uniform coverage consistently deeper than about 5 feet.  When in doubt, defer to simpler or lower-angled terrain choices as the potential avalanche size remains deadly.

The avalanche hazard has slowly relaxed over the past week resulting in a danger rating of MODERATE (level 2 of 5).  However, MODERATE does not mean safe conditions.  Explosive work continues to release large avalanches and reports of human-triggered avalanches continue to trickle in regionally like this one from yesterday near Marble.  Slabs and weak layers continue to exist on most aspects and elevations (except for some slopes that avalanched at the end of the last storm cycle thus removing the slab component).  So the real question is which slopes are you most likely to trigger an avalanche on?  Often this is a question of aspect or elevation but current conditions are not that simple or typical.

Since we know most slopes have slabs and many slopes have weak layers, your decision-making about which slopes you choose to play on is a question of likelihood.  Where you find that slabs are thinner, you will find an increased chance of triggering an avalanche.  You will more commonly find this snowpack setup with more trigger points in windward terrain where the wind has made the slab thickness variable, rocky terrain where terrain undulations make for variable slab thickness, or areas where the snowpack is simply shallower from less snowfall like low-elevation terrain in the Southeast Mountains forecast zone.  You can visually inspect terrain and make reasonable judgments about variable depth due to wind effect and you can often identify terrain with rocks and vegetation sticking through the slab.  You can also use your pole or probe to track snowpack depth as you travel to grasp the general depth in the area you are traveling.  The problem becomes trickier in some terrain where rocks or vegetation might be thinly buried below the snow surface and obscured from view thus leaving hidden trigger points.

The suggestion in the bottom line of utilizing depth as a gauge is a general rule.  Snowpacks in the 3 to 4-foot range are the most suspect for human triggering, however, even places with 150 cm (about 5 feet) could have hidden or obscured trigger points laced throughout the terrain.  Choosing uniform depth slopes greater than 150 cm is not a silver bullet, just simply a way to reduce your chances of triggering an avalanche.  Cracking and collapsing are clear indications you have found a dangerous snowpack and make it easy to defer to lower-angled terrain, but these overt signs have become infrequent.  

Don't let sunny skies, warm temperatures, and a positive weekend vibe distract you from making thoughtful decisions.  If you choose to step into avalanche terrain, do so carefully with a keen eye for terrain characteristics, snowpack depth, and potential consequences in case you choose wrong.