Large slide on N Castle Peak

Toured castle peak from the Boreal Exit this morning. On the ridgeline ascent we observed some active and recent wind loading with the skin track filling in and some small newly formed cornices along the ridge at 8,300 feet. Kicking at these smaller cornices cause them to brake fairly easily, kicking at these slopes also cause some localized windslab failure, max size 3feet wide 2 feet long 4 inches deep. We skied the backside of the castle peak observing a few small sloughs on steeper N facing terrain, but saw no other signs of instability, until the slide, other than some localized, and small, newly formed wind slabs. However, our search for unconsolidated snow largely kept us away from complex and heavily wind effected terrain. 

While skinning back up to the ridge between castle and basin peak we observed a large avalanche in close proximity to another party (snowmobilers and skiers/snowboarders).  It broke near the ridgeline and the crown extended 100+ feet down the slope. The side of the crown we could see was well over 100+ in width. The snow plume was quite remarkable and extended down to the meadow below. Our best guess was that in most places the crown was 4 feet tall. Several members of that party responded immediately to the area of the slide, however, we know no other details of the incident. The party did reconvene in the meadow below the slope 20 minutes after the slide, so we are hopefully everything worked out ok. 

We had also seen a crown of a smaller slide just to the east of the one mentioned earlier in the tour (final see photo). It appeared to be skier triggered, but we have less certainty about the details of this slide.  This slide seemed likely to have happened today day, the debris covered tracks already on the slope, and did have some tracks near the top of the crown.