Detailed Accident Report
Submitted By: GCAC; Steiner
Place: Marion Lake drainage in the Flathead Range
Summary: 1 skier caught, carried, partially buried, and injured. 1 dog buried and killed.
***OFFICIAL REPORT FROM the Glacier Country Avalanche Center***
05 Mar 2007
Skier Triggered Avalanche. One Skier Caught, carried, partially buried, and injured, one dog killed.
Avalanche Incident Overview:
On 3/3/07 at approximately 1400 two skiers and a dog entered an southeast facing avalanche path on Peak 7180 located on the west side of the Marion Lake drainage in the Flathead Range. The skiers had already skied a run on a north facing aspect of Essex Mountain without incident and were beginning their second run. The skiers were carrying avalanche transceivers, shovels and probe poles. They were well versed in avalanche awareness, avalanche rescue, and backcountry skiing.
At the time of incident, temperatures were in the mid 20s (degrees F) skies were cloudy, visibility was obscure, light snow was falling, and winds were light to moderate out of the west.
Prior to entering the path the skiers decided to ski cut the slope individually by traversing down slope, skier's left to right, under a well established cornice at the top of the path. The first skier traversed in with his dog weighting his skis as he skied until he reached the skier?s right side of the path. At this time he called back to his partner and he skied across to the first skier also testing the slope as he traversed.
Once together, the two skiers refined their plan by having the second skier back up along the skiers? entry line to an area that seemed safer to observe from and still spot the first skier. When the second skier was positioned, the first skier descended with his dog along the skier?s right flank of the path.
The first skier estimated he made eight (8) to ten (10) turns before encountering a steeper convex roll in the slope. At this point the skier stopped, with his dog right behind him, to evaluate the convexity and decided to traverse further to the right. Upon beginning his traverse, the slope above him and all around him began to break apart. The skier was able to ?surf? the slab for several seconds fighting to make it further to the right where he could grab a six inch (6?) diameter tree. After the initial few seconds, the skier lost a ski and began tumbling down the slope in what he estimated to be a five foot (5?) wall of snow. Losing control of his trajectory, the avalanche tossed him into the tree he was initially planning to grab. The skier came to rest partially buried but on top of the snow with his lost ski partially buried down slope from him. Although the first skier had impacted the tree forcefully with his pelvis and sustained injury, he was able to retrieve his ski and check on the status of the second skier and his dog. The dog was missing and there was no sign of it
The second skier fortunately was not caught nor injured. When the avalanche initiated, he saw the first skier and his dog get swept over the convex roll and then lost sight of them. Meanwhile, he turned back upslope and tried to get as far as possible from the moving snow. In retrospect, the avalanche fracture line had broken out from under the tail of his skis while he was turning around. When the avalanche came to a stop, he descended over the crown to assist the first skier.
Together, the first and second skier searched and probed for the lost dog for about two hours. The dog has not been recovered as of this time and is presumed to be dead, buried in the avalanche debris.
Although the skier caught in this avalanche was injured, he was able to leave the scene and ski out under his own power. In retrospect, no major injuries are suspected to have resulted from this incident to the first skier.
Post Avalanche Incident Investigation:
On 3/4/07 I went to the site of this avalanche occurrence and found that hang fire still existed in the upper skier?s left third of the avalanche path and two old ski tracks (from previous skiers) were still faintly visible in the hang fire on the skier?s left trimline of the starting zone.
The avalanche had released in the upper starting zone at approximately 7000 feet (7000?) (2121 meters) a.s.l. fracturing directly beneath the established cornice and what is now the remaining hang fire. Crown width was approximately 330 feet (330?) (100 meters). Crown depth ranged between two feet (2?) (.70 meters) and four feet (4?) (1.2 meters).
I conducted a crown profile on the skier?s left flank of starting zone at the base of the remaining hang fire on a 41 degree slope located along the base of hang fire. Crown depth at this location was 28 inches (28?) (72 cm). Failing layer was a crust/facet/crust layer. The first crust (1F hardness) had failed on 1.5 mm facets while the second crust (1F+ hardness) provided the bed surface. Stability tests at the crown consisted solely of compression tests the conclusively failed at CT20 with a Q1+ quality shear.
Average starting zone incline was 40 degrees with the convex roll incline averaging over 50 degrees. The starting zone had been loaded/ cross loaded with west/ southwest winds.
Convexity where avalanche was triggered was located approximately 200 feet (200?) (60 meters) down slope from where the first skier began skiing. Once caught, the first skier was carried an additional 250 feet (250?) (76 meters) to the tree he impacted.
The avalanche ran 1080 vertical feet (1080?) (327 meters) from 7000 feet (7000?) (2121 meters) a.s.l. to 5920 feet (5920?) (1794 meters).
Avalanche debris extended into trees on both sides of the path and ran full path and onto Marion lake fracturing the lake ice beneath it. Debris at the toe of the runout was approximately 150 feet (150?) (45 meters) in width and 10 feet (10?) (3 meters) in depth.
Avalanche Classification: SS-AS-R4-D3-O
Upon reaching the avalanche incident yesterday, an obvious naturally released avalanche had occurred on the next peak on the ridgeline to the south. This natural avalanche occurred on a similar aspect and elevation as the skier triggered avalanche and had been reported and recorded on the GCAC Inc. Regional Observations webpage on 2/25/07 by GCAC volunteer observer Mark Ambre. Unfortunately, the skiers had not recently viewed the Regional Observations webpage and due to obscured visibility, the natural avalanche was not visible to them.
Also visible yesterday from the Marion/ Dickey ridge was a large crown line that had zippered the east face of peak 7603 beneath Mount Liebig on Tunnel Ridge. Time of occurrence is not known.
If you have any questions, additions, and/or corrections regarding this avalanche incident, please call. (406) 212-0588
Ted Steiner, reporting for GCAC Inc.