Updated Information of Avalanche Incident in Canyon Creek – 2/25/2014
Avalanche Incident Report
Canyon Creek, Whitefish Range, MT
Date of Avalanche: 25 February 2014
Date of Investigation: 26 February 2014
INCIDENT SYNOPSIS (provided by a member of the party involved)
At 15:00 on 2/25/14 I was part of a three person snowboarding group that was caught in an avalanche in the Canyon Creek area in the Whitefish Range. At 14:00 we hiked Flower Point and dug a pit on a ENE Aspect, 35 degree slope. We found a weak layer about 50cm down from the surface. Our stability tests showed CT24Q3, ECTP22Q3. We rode the ridge out toward Banana Chutes and dropped into the Canyon approximately 300yds skiers right of Banana Chutes. We reached the bottom, quickly rechecked our beacons and began hiking out back to chair 7. At 15:00, just as we were reaching the top of the hike out, we heard a boom and an avalanche descended on us from the opposite face we rode (Skookoleel ridge, fiberglass hill). The avalanche missed me by about 20 feet but caught the other two members of my party. One person was swept off his feet but was able to swim out of it and was not buried. The second person was also swept off his feet and was buried with only his head and one arm sticking out. We were able to quickly locate and dig this person out. No one in our group was seriously injured and we were all wearing beacons and had shovels and probes.
SS-NO-R3-D2.5-O (Comments on classification: After investigating the avalanche and based on statement from those involved, we decided to classify the avalanche as a natural trigger. All evidence suggests it was a natural avalanche. We were unable to find any tracks above the crown. We were on the ridge on the opposite side of the canyon just prior to the avalanche release, but did not witness it. We observed a small loose sluff on the slope prior to the slab release. It is possible that a small sluff from the rocks on the slope could have triggered the slide, but aside from the sluff we observed that already existed we observed no other evidence of sluffing.)
This was the second avalanche incident involving partial burials in Canyon Creek within 10 days.
Widest part from flank to flank: 233 m (766 ft.)
Crown depth: Avg. 70 cm (28 in.), Maximum 100 cm (39 in.)
Vertical fall: 183 m (600 ft.)
Ground distance: 255 m (840 ft.)
Debris pile width (max.): 260 m (850 ft.)
Debris depth: 160-200 cm
Failure layer: Faceted snow (FC) above melt-freeze (MF) crust from late January.
Slope angle at crown: 39°
HS (height of snow) at crown = 165 -218 cm (65 – 79 in.)
Aspect at portion of crown investigated: 209°
Thanks to Craig Moore (GlacierWorld.com) for providing overview images of the incident site. Please contact Craig for permission to use those images. All other images are courtesy of Flathead Avalanche Center (see images at end of report).
WEATHER AND SNOWPACK
Beginning February 1, 2014, an arctic air mass parked itself over the region until around February 10, 2014. Prior to this a melt-freeze crust formed on sunny aspects throughout the advisory area. Small accumulations of snow occurred periodically and fell on this crust. During the cold air outbreak, the surface and near surface snow became weak and faceted causing weak layers to form on top of the melt freeze crust. The next notable precipitation commenced the afternoon of February 10, 2014 and snow accumulated incrementally through February 22, 2014. During that arctic outbreak mountain temperatures reached below -20 °F. When the cold air mass exited the region, temperatures rose with new snowfall throughout the advisory area. A special avalanche bulletin was issued on Thursday, February 20, 2014 to advise backcountry travelers of elevated avalanche danger through the weekend.
The most recent avalanche advisory prior to the incident was issued Sunday, February 23, 2014. The bottom line read:
“For today the avalanche hazard is rated as CONSIDERABLE. Human triggered avalanches are LIKELY and natural avalanches are possible. Dangerous avalanche conditions still exist. The late January crust/facet layer still exists 2-4 feet deep and poses a potentially dangerous persistent slab problem. Careful snow pack evaluation, cautious route finding, and conservative decision making remain essential. Staying out of the runout zones, especially terrain traps, is important.
Note: We are in a period of tricky and potentially dangerous avalanche conditions. Many of us are powder starved and waiting to get into the backcountry. We need to ease back into the backcountry to see what is in store. Approach slopes today with caution and treat them as suspect until you can prove otherwise. Given the uncertain nature of persistent slab, they deserve a wide margin of safety.”
Another cold air mass infiltrated the region 48 hours prior to the avalanche causing mountain temperatures to reach -13 °F. Clear skies, intense solar input, and rising temperatures (above freezing in some locations) occurred on the day of the avalanche (February 25). The closest reliable mountain weather stations that provides hourly data is Hand Creek SNOTEL (elev. 5035 ft. and ~40 km to the southwest of the incident site) and Stahl Peak SNOTEL (elev6030 ft. and ~60 km to the northwest).
FAC staff received a report of an avalanche in Canyon Creek around 4:00 p.m. from a member of the Whitefish Mountain Ski Patrol. FAC staff spoke with one of the individuals involved in the avalanche later that evening and he reported that all individuals involved were uninjured and safe. FAC staff visited the incident site the next day on Wednesday, February 26 and completed a fracture line profile on a southwest aspect (209 degrees) and found an approximately 70 – 100 cm (28 – 39 in.) slab sitting on a layer of faceted crystals over a 1 inch (3 cm) thick melt-freeze crust. The bed surface of the avalanche was the melt-freeze crust.
Stability tests on the crown: ECTP 28 Q1 (failure layer was the facets above the melt-freeze crust). This is the same snow structure (weak layer and bed surface) of two reported human triggered avalanches just three days prior. The snow profile of one of the incidents in nearby Depuy Creek shows the same structure.
The staff at the Flathead Avalanche Center wish to extend our gratitude to those involved for providing their first-hand account of the events. This information helps all of us learn in the context of a real situation, and helps promote sound backcountry decision making.
SEARCH AND RESCUE
No search and rescue operations were initiated as the individuals involved were able to extricate themselves.
Direct any questions regarding this report to email@example.com or 406.261.9873.
Report prepared by Erich Peitzsch of the Flathead Avalanche Center. Special thanks to Ted Steiner for assisting in the investigation.
All formal notation and recording guidelines can be found in:
Greene, Ethan M., D. Atkins, K. Birkeland, K. Elder, C. Landry, B. Lazar, I. McCammon, M. Moore, D. Sharaf, C. Sterbenz, B. Tremper, and K. Williams, 2010. Snow, Weather, and Avalanches: Observational Guidelines for Avalanche Programs in the United States. American Avalanche Association, Pagosa Springs, CO: Second Printing Fall 2010, 152 pp.