Public Observation - Storm Slab Avalanche in Chicken Bones, southern Whitefish Range

Walked over from the Flower Point Chair out Ghoolies to the southeast facing terrain (Chicken Bones) and took a few laps.  The afternoon was fairly foggy with light snow (no wind) but by our third lap the visibility was good and the temperature was warming up slightly.  First two laps we experienced soft powdery turns expect for a small point release on a steeper cliff area.  On our last descent two of us rode the first open section around a blind roll over/medium size cliff and waited for the third skier to discuss the pitch below.   From where we were standing the terrain below included some small roll over cliffs with a large apron down to the thick tree line.  Without having clear communication with the third skier we were unable to let him know where we had stopped and what terrain was above us (skiers left of our tracks).  As the third skier traversed along the slope left of our tracks he came across the convex slope and around a 10-12 inch crown (storm slab) propagated across the shallow/rocky terrain.  Not knowing where the third skier was heading we heard from below "Avalanche" and as I saw the snow cascading over the cliff above I turned downhill and grabbed the large tree directly below me.  The other snowboarder was about 25 feet away to the skiers right with no trees near and luckily did not get fully buried (was able to stand up after the snow settled) or dragged down the slope.  The snow ran all the way down to the large apron below and settled down by the tree line.  We skied the path of the slide down and cut out to the right through the trees and skinned back to the resort.  None of us were surprised where the storm slab propagated or triggered.  While digging a pit earlier in the afternoon we talked about the risk of convex/wind slab slopes.  The problem was we did not have a clear plan on where we all wanted to ski/snowboard before dropping.  With the warming trend continuing be safe out there!