The avalanche that occurred on Sunday is a good reminder that even during relatively low avalanche danger, avalanches can happen, even natural ones. Thankfully no one was seriously injured. Click here for a thoughtful detailed account from the party involved. While the avalanche danger was unlikely for that day, this avalanche did occur in the type of terrain that the advisory mentioned would be possible for wind slabs that day. We don’t know for certain what triggered this natural release on this SE facing terrain, but it seems very likely that is was a wind slab recently formed by strong NE ridge-top winds. Perhaps it was simply current wind loading that overburdened the slope. Perhaps there was a weak layer underneath involved. Perhaps the mid-day sun and relatively warm air temperatures warmed the slope enough to cause an already fragile structure to fail. Regardless of the exact cause, the message is not to let your guard down in the mountains.
Clear and cold nighttime conditions thru this week will continue the faceting and weakening of our thin snowpack. While not a stability concern now, if we get 1-2ft of new snow-load this weekend, it could definitely become one. Keep digging into the snowpack to see where this sugary facet formation is happening. Also, feathery surface hoar formation has been reported on the surface of the snow in some places over the weekend. This can become a dangerous weak layer if it persists on slopes steep enough to avalanche if it gets buried. Please let us know if you see any of these feathery formations persisting on slopes.
