Observer Name
UAC Staff
Observation Date
Tuesday, December 31, 2024
Avalanche Date
Saturday, December 28, 2024
Region
Salt Lake » Mill Creek Canyon » Porter Fork » Main Porter
Location Name or Route
Porter Fork Pass
Elevation
9,400'
Aspect
Northwest
Slope Angle
37°
Trigger
Unknown
Avalanche Type
Soft Slab
Avalanche Problem
Persistent Weak Layer
Weak Layer
Facets
Depth
18"
Width
70'
Vertical
300'
Caught
1
Carried
1
Buried - Fully
1
Killed
1
Accident and Rescue Summary
As the avalanche victim was traveling solo, there are many unanswered questions. To further complicate the picture, avalanche danger prevented avalanche forecasters from accessing the accident site and avalanche information is either estimated or conjectured via photos, snowpack history, and discussions with search and rescue personnel.
On Saturday, December 28th, a backcountry skier in Porter Fork found an unattended dog wandering in the drainage.
On Sunday, December 29, Salt Lake County Sheriff’s Department, and Salt Lake County Search and Rescue (SLCOSAR) started an investigation for a missing person. They also received reports of an out-of-state van that had been unattended for a couple of days in the Porter Fork parking lot. The microchip on the dog’s collar and license plate data provided information on the owner and the dog’s tracks through the mountains. Cell phone “pings” targeted by the cell phone provider also provided some GPS information to narrow the search areas within Porter Fork further. Ground teams searched cabins in the lower portions of the drainage for the individual. In the afternoon, a backcountry skier (we'll call him The Good Samaritan). who commonly skis in the area saw the Sheriff’s social media post and remembered seeing an avalanche debris pile just below Porter Fork Pass and the western slope of Mt Raymond.
On Monday, December 30, while ground teams searched the low to mid-elevation areas in Porter Fork, investigators used social media to inquire about any sightings of the missing individual in that area. The avalanche danger was rated as HIGH, limiting search areas from the ground. A helicopter armed with a long-range receiver flew over likely search areas but did not detect any transmissions. By late afternoon, acting on his hunch, The Good Samaritan and a partner traveled up to Main Porter Fork to the debris pile, conducted a beacon search, and uncovered the victim, who by this time had most likely been buried for nearly 36 hours. The Good Samaritan returned to the trailhead by 6 PM to alert the SAR teams.
(Photo: This was taken Sunday by the good Samaritan. At the time he did not realize someone was buried in this avalanche.)
On Tuesday, December 31, SLCOSAR teams utilized Utah Department of Public Safety and Life Flight helicopters to insert two rescuers and a spotter to the ridge above the accident site. An hour before, avalanche mitigation teams flew in and dropped explosives to trigger avalanches to make the area safe for rescue teams. The explosives triggered four avalanches in the area, giving rescuers room to conduct the extraction of the body to the Incident Command Post in the valley.
As the individual was traveling solo (other than with his dog), only conjecture can offer any sort of narrative of the chain of events. David Ethier, thirty-eight years old and hailing from Quebec, Canada, was on a road trip in the western US with his dog. Research indicates he was a mountain athlete and backcountry snowboarder. David had climbed Mt Olympus in the Wasatch the day before the accident. On Saturday, December 28, David began his outing into Porter Fork of Millcreek Canyon, proceeding up Main Porter Fork to reach Porter Fork Pass at 9,300'. It was reported that other tracks were in the area and perhaps, wanting more fresh tracks, he ascended the ridge to the east to gain more elevation. At this point, David put his splitboard together, stowed his ski poles, and rode down his chosen line. We do not know anything about how the avalanche was triggered. All we know, is that they were caught, carried, and buried in an avalanche. Photographs from the site indicate a soft slab of wind-drifted snow, perhaps 1-2 feet deep and 70 feet wide, that likely failed on a persistent weak layer of faceted grains. This was on a steep northwest-facing slope at 9400’. His black lab was found by another backcountry skier later in the afternoon of December 28.
Terrain Summary
Millcreek Canyon is located in Salt Lake City, Utah, roughly sixteen miles east of the SLC International Airport. The trailhead for Porter Fork is four miles from the entrance to Millcreek Canyon. Main Porter Fork is a three-mile canyon with roughly three thousand vertical feet of elevation gain from the parking lot to Porter Fork Pass at 9,300'. It has many large and steep avalanche paths throughout its length. See photo two below for slope angle shading that highlights the many avalanche paths.
Weather Conditions and History
Until December 13, 2024, northern Utah had been below average in snowfall (as the storm track has been north of the state) with only small amounts of snow. A shallow snowpack, cold temperatures, and clear skies created a snowpack consisting of weak, faceted crystals on mid and upper-elevation northerly-facing terrain. The avalanche danger was rated Moderate through this period as there was no slab of stronger snow over the faceted snowpack.
A four-day storm starting on December 13 was the first significant load on the weak snowpack. Alta Collins SNOTEL site (9,600') reported 17 inches of snow with 1.15 inches of snow water equivalent. This storm elevated the avalanche danger to Considerable from December 14-19.
On December 19, UAC forecaster Greg Gagne did field work just below the accident site. A snowpit profile and accompanying photo shown below (photos 1 and 2) demonstrate the weak structure of the faceted snowpack that developed during the prolonged period of cold, clear weather. All that was lacking was a slab of stronger snow on top of this weak structure.
Starting on December 25, a large-scale pattern shift was forecast, with strong winds and heavy snowfall expected through the New Year. This is when the slab really grew in size, still sitting atop the weak layer of faceted snow. On the morning of the December 27, winds were from the southwest, averaging 15 to 20 mph with gusts into the 30s and 40s at the Reynolds Weather Station (9,400'), approximately three miles east of the accident site (see photo 3 below). The Millcreek SNOTEL site reported six inches of new snow with 0.80 inches of snow water equivalent on the morning of December 27th.
We believe the avalanche was a stronger slab of wind-drifted and dense storm snow that failed in the buried weak, faceted snow. The terrain on the south side of Porter Fork Pass would have been the perfect fetch for southwest winds to load snow onto the slope where the accident occurred.
Below are the wind and temperature runs from Reynolds Peak (9400') December 23rd - December 28th, 2024.
Comments
Decision Making: As the avalanche victim was traveling solo, there are unanswered questions and we do not know anything about his decision-making process before the accident. On the day of the accident, the avalanche danger was rated as HIGH for this aspect and elevation, an avalanche warning was in effect, and the primary avalanche concern in the avalanche forecast was the buried persistent weak layer of snow.
We are saddened by this tragedy, and we write these accident reports to hopefully learn more about backcountry accidents. We are thankful for everyone's help in the rescue efforts. Many organizations and people helped find and locate this person.
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