Southeast Mountains

The chance of triggering a large avalanche breaking on weak layers near the ground continues to slowly decrease under our dry weather pattern.  You are more likely to trigger a dangerous avalanche from a shallow spot on the slope where slabs become thinner: be cautious of steep slopes holding variable snow depths due to rocky terrain or wind effects.  Because trigger points aren't easy to identify, and because the consequences are deadly, give yourself a larger margin for error than normal when assessing the snowpack and choosing terrain.  

This month, we've observed 280 large to very large avalanches (D2 to D3 in size).  Amazingly, only 5 of those avalanches have been human-triggered.   That's in part because of cautious travel habits (nice work Gunnison Valley!) and in part because weak layers have been getting deeper and harder to trigger now.  The avalanche danger has trended down to MODERATE in recent days because natural persistent slab activity has tapered off.   With increasing winds today, we can't rule out the isolated potential for another large natural avalanche on a leeward slope. The danger will be increasing tomorrow with fresh snow to fuel wind transport. 

Although our persistent slab problem has become more difficult to trigger, it demands serious caution because of the high consequences.  We are only a couple of days out since our last reported persistent slab activity (explosive triggered on Wednesday, naturals on Tuesday).   Some slopes are finding equilibrium now under the past few days of quiet weather.  Some slopes will require a large trigger such as a cornice fall or tunneling your snowmobile's track deep into the slab.  And some slopes can be triggered by the weight of a person crossing the wrong spot on the slope.  This video describes how you can trigger a large avalanche by collapsing the weak layer from where slabs thin out.   Signs of instability and persistent slab activity have been more common this past week in the Southeast Mountains, where the snowpack is generally shallower and weak layers are a bit worse.   However, we are still finding poor structures and concerning pit results in both the Northwest Mountains (example) and Southeast Mountains (example).  Under low likelihood, high consequence scenarios, we often get drawn into more aggressive-than-planned terrain because the snowpack feels stable and the danger is not staring us in the eye.  Here are a few strategies for reducing your risk if you and your group have avalanche terrain in mind.

• Verbalize "off-limits" terrain with your partners before you leave the trailhead and stick to it, regardless of what the snowpack is telling you.  Snowpit results and snowpack structures are variable right now due to previous avalanche activity, winds, etc - don't trust your life to one result. 
• Stay in terrain where the snowpack is deep and uniform. Avoid areas where the wind has varied the thickness of slabs. Avoid shallow rocky areas.
• Set your up-tracks out of harm's way.  This season, about 40% of the ski touring avalanche fatalities have occurred while ascending.  You are more vulnerable going uphill and it is harder to travel one at a time.
• Re-evaluate your safe zones so that they are appropriate for our unusually wide propagating avalanche conditions.  There have been four multi-party fatality accidents in the US this year, and a couple of accidents where 8 people were caught all at once.  Your normal regrouping spots may not be safe. 

Remember that when the snowpack is the question, terrain is the answer. You can always have a low-stress, safe day by staying on slope angles less than 30 degrees that don't connect to steeper terrain above, while waiting for a more trustworthy spring snowpack.