Crystal Creek 2/7/13

Please read the account of an incident that occurred up Crystal Creek in the Middle Fork about 3 PM on Thursday.  Thankfully, nobody was hurt and Mike and his group were willing to share their story.  We are initially classifying the avalanche as a SS-AS-R2/D2-O (Soft Slab- Skier Triggered- Small relative to path/Could bury injure or kill a person-the avalanche released within the Old snow).  Mike relayed that he believes the fracture was mostly wind loaded snow on top of a previous sun crust and that he did not believe there were any impacts of solar warming on that aspect Thursday.  Remember that Moderate Danger still means human triggered avalanches are possible. 

Mike Bussard 
  
“Just wanted to send a brief account of an incident that occurred on Thursday feb. 7th.
Three of us, 2 skiers and 1 split boarder, toured up Cascadilla Creek on Thursday morning. Skies were clear and temps just below freezing. We saw many up and down tracks from the previous few days but all traces of tracks were gone by the time we reached open terrain. On the way up Cascadilla we noted a smooth crust underlying fairly light fresh snow. We climbed to the low point in the ridge between Cascadilla and Crystal Creek. Climbing the ridge we noted significant wind loading on the north aspect. The snow below the ridge felt unconsolidated but given the crust and the loading we decided to stay off the steep north slopes. Aside from that we saw no signs of instabilities or recent avalanches. We skied two long runs on the mostly east facing terrain at the head of Crystal. We were careful to avoid the convexities and lee sides of ridges we thought might be cross loaded. The sun was affecting the southern slopes causing a few roller balls but the eastern aspect seemed unaffected. On our third run we traversed further out in to the open terrain and skied down to a prominent point mid slope. We noticed a steep convexity below and discussed the safest way on the skiers right side. the snow boarder rode down and and left to a predetermined spot on a small ridge to spot. I then skied down staying in his track until past the steep roll over and then proceeded about 900 vertical feet to the bottom of the slope. As I was moving to a safer spot the third skier dropped in a little left of the first two tracks and the snow fractured. The crown was about 20 feet wide and maybe 4 inches deep, and only ran a few yards. The triggering skier saw this happening and skied far out right towards some small trees. He inadvertently skied on to an even steeper slope and stopped to look back. As he stopped, the slope he was on fractured a few feet above and he was instantly swept with it. This second crown was about 60 feet wide at the widest, and varied in depth from a few inches to about 2 feet on the skiers right flank. It ran about 300 feet. The skier managed to stay on his feet for about 80 feet and then fell and was dragged about another 100 feet tumbling with the snow washing over him several times. He came to a rest on top of the debris and the snow traveled another 100 feet or so and spread out over the even slope. He was uninjured but lost one pole and a ski. The ski was found about 60 feet below jutting half out of the snow. The pole wasn’t found. It seems that part of the slope was cross loaded from a slight ridge above and south. After debriefing we climbed back to the ridge and more or less followed our skin track out Cascadilla.
Looking back we may have been a bit affected by sunshine powder syndrome and forgot how much tiny aspect changes can affect snow pack. We did not dig any pits but were aware of this particular possible instability and had discussed it several times. Seeing that no one was injured this was a good reminder for us all. If there had been a trap of any sort, there would have been more than enough snow to bury a person. “

Crystal_Creek_2_7_13

Crystal Creek Vicinity

Update for Elk Mountain Avalanche Jan 8

UPDATE to avalanche incident investigation on Elk Mountain, Glacier National Park, Montana as reported by Erich Pietzsch.

A full incident report will follow in the next few days. We are providing this information so backcountry travelers are aware of the conditions that led to this avalanche incident.

The avalanche occurred on the afternoon of Wednesday, January 8, 2013. The following day (January 9) a team of 3 avalanche specialists and a district ranger from the U.S. Forest Service, the U.S. Geological Survey, and Glacier National Park along with a member of the party involved traveled to the scene of the incident. The scene was located along the main south side of Elk Mountain along the southern edge of Glacier National Park, Montana. Lack of visibility, moderate to strong winds, and substantial new snow limited our ability to access and document the entire accident site. However, with a member of the part accompanying us, we were able to access a lower part of an avalanche crown. Based on conversation with the party, there were actually two separate avalanches that occurred at two separate times but in adjacent gullies. We investigated the snowpack along the lower edge of the avalanche that did not involve the party. However, this avalanche was witnessed by a member of the party earlier in the day.

Investigating the crown proved a bit difficult due to new snowfall and snow loading at the crown. The avalanche occurred on a south-southeast facing slope on the south side of Elk Mountain in an area locally known as “The Backstrap” and funneled into a gully. The average slope angle of the starting zone was approximately 35 degrees and the alpha angle was 32.5 degrees. Avalanche dimensions were also difficult to determine due to conditions, but the crown face depth appeared to range from 12 to 36 inches deep and the avalanche was approximately 145 feet wide and ran approximately 1400 vertical feet. The crown was located at approximately 7200 feet in elevation and the toe of the debris was around 5800 feet. The caught skier was carried approximately 800 vertical feet. US classification of the avalanche is SS-ASu-R4-D2-I. We found six to ten inches of new snow that had fallen by late morning of January 9. This new snow covered up a substantial portion of both the avalanche crown and the debris. We performed a snow profile along the crown as well as multiple Extended Column Tests (ECTs). Our extended column tests resulted in propagation of a fracture just above an ice crust. At the location of the crown we investigated, we found about a one meter (39 inches) wind slab sitting on top of this weak layer. The weak layer appeared to be a layer of small facets sitting on top of this ice crust. This ice crust may potentially be a sun crust that formed on January 3. The weather and snow conditions leading up to this incident produced wind slabs, sometimes very sensitive, sitting on top of a variety of layers including crusts and facets. More detailed information will be available in the full incident report. Be safe.

 VIDEO:

http://www.youtube.com/watch?v=Yhw03-N5t4E

 

Skier Triggered Avalanche – Jewel Basin

Report of a skier triggered avalanche in the Jewel Basin today. 25 Dec.

Early reports indicate the skier was caught but not injured. Soft slab avalanche that initiated on a wind slab/on some buried surface hoar approx. 25 cm down. Slide ran approx. 200 feet. More information to follow. Be careful out there. 
 
Update:  From phone conversation with reporting party.
Two experienced persons (1 skier and 1 snowboarder) were touring on their way up to the radio tower near Mount Aeneas.  They decided to ski a NE aspect slope that drops into Crown Bowl.  They had noticed no signs of instability during the ascent.  They dug a pit and performed a compression test in the start zone.  The results from the test did not indicate instability in the snow pack.  The skier dropped in first and made 3 turns when the he triggered the slide.  The skier was carried approximately 100-150 feet where he ended up about waste deep in the debris, uninjured.
The avalanche was a SS-ASu-D2-O.  Soft Slab- Skier triggered, unintentional- (D2) size could bury, injure or kill a person. 
Slide crown was 4 inches (10 cm) on one flank and 10 to 12 inches (25-30 cm) on the other flank and it went approximately 300 feet. 
Report is that there was a wind slab on top of some faceted grains.
 
Remember even very experienced backcountry users that are taking all the right precautions and making the best decisions they can with the information they can gather, can be surprised.
Use caution when entering slopes from ridgetops avoiding convex rolls and wind slabs.