Northwest Mountains

The snowpack is trending in the right direction, but weak layers near the ground are still capable of producing avalanches, such as this skier-triggered persistent slab yesterday on Cinnamon.   On previously windloaded slopes or sheltered northerly terrain where the snowpack is deeper than about 2 feet, stick to smaller features, clean runouts, or lower-angle slopes to keep the odds in your favor in case you get surprised. 

Observers reported a couple of notable avalanches yesterday: a skier-triggered persistent slab near Paradise Divide and what appears to be a recent natural persistent slab off of Cascade Peak.  Although reports of cracking/collapsing have waned to isolated or none in the past few days, these avalanches show the problem still exists.  The troublesome aspects are well defined by the pattern of persistent slab avalanche activity in the past two weeks and by thorough documentation of weak November snow surfaces before burial.  More recently, we've seen the issue become more confined to near and above treeline where slabs are robust enough to survive ongoing faceting.  

The early December storms added 3.5" of SWE at Irwin, whereas Butte Snotel at CBMR picked up 1.7" SWE onto a layer that was equally fragile across the forecast zone.  With roughly twice the snow load in the Northwest Mountains, slabs are both larger and more common throughout the terrain, and more resilient to the decaying process.  As time goes on and the snowpack continues to adjust, both zones are seeing a gradual decline in the danger.  The Southeast Mountains are the first to move to Low: fewer slopes harbor the problem, and where it exists, avalanches are typically smaller.  With thin snowpacks, even small avalanches that drag you over rocks and logs can have serious consequences, so don't let your guard down.  In the Northwest Mountains, travel in avalanche terrain requires a bit more caution for now, as slabs are typically thicker and more continuous across the terrain.