Avalanche: Turnagain

Avalanche details provided by B Finley:
The avalanche failed to the ground and propagated widely.  It took out our ski tracks down the West Face and portions of the skin track near the base of the run.  It also propagated partially around to the south side of the peak. Looking back up at the bed surface it is apparent that the SW ridge has several rock bands that could have acted as a trigger point.
 
There was a sympathetic slide on the North side of Cornbiscuit during this event. Another group had eyes on it. A few people in the skin track to PMS bowl were hit by the powder cloud.
 
The debris pile was probably 10' deep at the bottom of the SW ridge.  It funneled through the alders and came to a stop just below the alder band.  Further south the debris flowed several hundred feet further towards Bertha Creek.  

Account from group of 3 involved in avalanche on SW face:

"We were a group of 3 experienced skiers and were just planning on getting some powdery laps in a spot that has been getting a lot of skier visits (I skied it a couple weekends ago). We were behind about a dozen other folks as we left the parking lot. No noticeable signs of instability other than the large releases that were listed in the avy report. We followed the ski track up the NW ridge/face(?). I generally hate that route due to all the thin spots that could trigger something and usually prefer to go around and up the SW side. But we saw many folks headed up and no signs of any releases, so we followed the established route. No issues or red flags on the skin up. Once we got to the final flat spot before the summit ridge, we stopped and decided NOT to follow the half dozen or so people that kept climbing and heading back on the CB ridge line. Again, we were just going to get a quick powder lap in to see how things felt. I made a couple turns down the SW ridge/roll and stopped to take some photos. My friends then skied by me for a quick snap and continued down the slope. I put my phone away, put my gloves back on, grabbed my poles, and then made one more turn on the ridge to reestablish a line of sight to my partners. Sliding to a mellow stop where I got eyes on my buddies, the slope cracked 18” downhill from my skis and the crack ran rapidly in both directions. I saw the entire snowpack, down to the ground, begin to slide. I yelled avalanche repeatedly, but my friends were way too far down the slope to hear anything. However, people on the skin track did hear me shouting. I didn’t move while I kept my eyes on both my partners. One member broke skiers right and only got hit by a bit of the powder cloud. He was able to yell “avalanche” just before that and the second skier heard that shout and broke skiers left away from, what he thought was the main slide. Unfortunately, he turned back toward the bulk of the debris and was immediately hit by the avy. I had eyes on both until the powder cloud obscured my view of the bottom of the entire run. Once the cloud passed, I assessed where I was standing and whether or not it was safe to begin my visual search and ski towards the last known point for the second skier. Since it ripped to, basically, the ground, I felt that it was safe to ski the bed surface. I began shouting to everyone on the skin track to get their beacons in search mode and not ski anything in the area while I was looking for my friend. The second skier lost his gear after getting hit by the powder blast and began tumbling in the main part of the slide. He was only carried 30-50 meters as he was already almost down at the alders when the avalanche struck him. He had beacon, shovel, probe, but no airbag. He managed to swim to the surface while things were moving and then came to the top just as the snow stopped. I was about halfway down the slope when I saw him stand up. I shouted and he replied with the “ok” hand signal. I shouted to everyone on the skin track that both my partners were accounted for. I continued to ski down to aid the second skier as I assumed he had lost all his gear. We did a quick medical check and all seemed to be ok, so I immediately gave him one of my skies and we one-skied it back out to the car. Back in the parking lot, we saw Billy Finley return a bit later and he mentioned they had done an additional beacon search and someone had located the missing pair of skis. We discussed what happened with him and then thanked everyone for returning the skis."

The following report by Billy Finley, who was with another group:

We toured up the standard (W face) up-track to the top of the western most bump of Cornbiscuit.  We were a group of 3 and 2 others were right behind us.  All 5 of us skied the West Face staying skiers right of the Southwest Ridge.  At the bottom we transitioned and then began going up for a second lap.  We were 2/3 of the way up when we felt a collapse.  We turned around to see a powder cloud below us and a skier outrunning the slide.  Luckily all 5 of us (on the up-track) were safe from the slide path.  We pulled skins and skied to the bottom where we regrouped.

The avalanche was triggered by a party of 3 skiing the SW ridge.  One of skiers was able to stay on top of the run and ski down the bed surface.  Another skier was able to outrun the slide by skiing right (west).  A third skier attempted to the left towards Bertha Creek and was caught in the slide.  He lost his skis and was caught in the debris before coming to the rest in the alders at the base of the run. He was able to self-rescue but his skis were lost.

Once we noted that the skiers who were involved were safe we ascended back to the debris.  A group of 7 did a thorough beacon search in the debris path just to be safe. The lost skis were recovered (near the base of the debris pile) and returned to the owner.

A couple of notes about this day:

- Our group did not have radios. I’ve always made excuses when it comes to radios and I need to stop making those excuses and always carry them.  Luckily another party had a radio and leant it to the people doing the beacon search.  We were then able to communicate with spotters at both the top and bottom. (Incidentally on of the key points from the 2008 near-miss on Cornbiscuit was “bring radios”.)

- There is a bit of debate in the community about whether the W face or N ridge up-track on Cornbiscuit is safer.  The N ridge climbs over several steep rock bands and is exposed to weather from two sides.  It fails on the regular basis and the bottom of the up-track is a terrain trap.  The W face on the other other hand rarely fails - but when it does it tends to go big and the up-track can get buried. Likewise the W face up-track is exposed to skiers descending from above.  My take-away from this is that Cornbiscuit doesn’t have a safe up-track.  If you are worried about conditions and are looking for a safe up-track you won’t find one - so best to save it for days when you know conditions are solid.