SEQUENCE OF EVENTS
I was planning field work on the day of the incident and went to do our procedural “check out” where we document our field work plan. My phone wouldn’t connect to the internet for some reason, so I called the Forecaster on Duty, Evelyn, and spoke with her directly to inform her of my intentions. A recent storm had moved through on January 31st. The wind had blown from the southwest then switched to the southeast in the 30 mph range during the storm. The wind blew from the northwest in the 25 mph range for a number of hours on February 1st. The skies were clear with light north wind in the 10 to 15 mph range on the day of the incident
I met a friend and his wife who were planning on skiing on the Manti Skyline. We met at the Miller Flat parking lot around noon to decide where to go. I suggested that we go into Huntington Canyon for a couple of reasons.
The storm that had just moved through had a southeast flow and I was interested to see if Huntington Canyon had been favored with snow from the orographic effect.
It was a late start and it would be easy for us to walk on skis directly from the road rather than travel on sleds as I often do on the Skyline.
There are many safe, low angle gladed slopes for fieldwork and skiing.
In Huntington Canyon we selected a slope with a steepness of 25 to 30 degrees and no exposure to avalanche hazard. We agreed to ascend the 1000 foot glade and descend the same route. I found less new snow than anticipated. I had heard reports of up to 14” of new snow. I found an average of 6”.
As we ascended, we noticed that the snow surface was wind affected on the upper third of the slope. Also as we were ascending, I was doing my usual sniffing around in the snow which included poking it with my pole to feel the layering, doing quick hand pits to investigate the new snow, and digging through the entire snowpack for more detailed observations. The snowpack structure was as I expected. It consisted of 8 to 10 inches of well developed faceted snow with 1 to 2 feet of more consolidated snow on top of it. My shear and propagation tests produced no alarming results. A compression test results showed a Q2 shear after 10 to 15 taps. Extended column tests yielded no propagation in the weak snow near the ground.
Since November, I have been monitoring the snowpack in this area which is more shallow than other parts of the Manti-Skyline. The snowpack seems to always be very weak but rarely gets overloaded by large amounts of new snow. Huntington Canyon is on the lee side of the range which doesn’t receive as much snow, and avalanche events are infrequent.
At the top of the slope, we discussed our descent. My friend’s wife is not a strong skier and descending the wind affected snow of our ascent route was going to be difficult. Vegetation sticking through the snow would add to the difficulty. We decided to look for an alternate descent route with easier skiing and less vegetation.
The alternative was unfamiliar, steeper terrain adjacent to our ascent route. This terrain is steeper and capable of producing avalanches but I thought that we would be able to find a route that avoided the steepest parts of the slope.
The slope starts out relatively flat, steepens mid slope, then lessens in angle further down slope. This convex shape prevented us from seeing the entire slope from the top. Each person would ski through the steeper mid slope section and regroup in a safe zone below the steep portion. We could all see the safe zone from the top.
I skied first and found about 6” of new snow that was not wind affected. It was easy skiing at the top. As I descended, the terrain became steeper than I anticipated and made me nervous. Also, the new snow became thicker, indicating wind effect. This thick snow made me nervous because wind affected snow is more likely to avalanche than non-wind affected snow. Because the slope was steeper and more wind affected than anticipated, I slowed and looked for an alternative descent. There were no alternatives. In a split second decision, I decided to rapidly descend 200 or 300 feet of steeper terrain into the safe zone below and left of my current position. Before I could act, the slope fractured.
Knowing I triggered an avalanche, I lunged for a tree, but missed it by inches. I fell on my side on top of the slab as it started sliding downhill. It started slow and I had time to think but I was unable to do anything. As it gained speed and started to break apart, I was submerged under the debris. At this time my skis were still on my feet and were pulling me down. I kicked my feet hard against each other and the skis released. I started to swim in the debris and surprisingly found myself briefly on the surface. A second wave of debris pushed me under the snow again. This wave felt much heavier than the first and I felt the speed increase. I was frightened, thinking that a massive amount of snow had released above me and I was going to be buried very deep. I kept struggling and trying to swim. It felt futile but I kept fighting. I was under the snow with a lot of pressure on my body when I felt the debris slowing down. I continued fighting and suddenly felt the pressure decrease until I surfaced at the toe of the debris.
I brushed snow off of my body, pulled my feet out of the debris and stood up. My friend descended the track of the avalanche with his avalanche transceiver in receive mode. When he reached me, we moved off the track of the avalanche path. I lost my skis and poles. The toe of the debris was only about 200 yards from our trucks. I walked through the snow on my own although I had a dislocated shoulder and substantial knee damage.
We went to the Intermountain Healthcare medical clinic in Mount Pleasant where medical staff took x-rays of my right shoulder and reduced the dislocation. A few days later, the University of Utah Orthopedic Clinic examined my right knee which had a damaged MCL ligament and a completely torn ACL ligament.
SNOWPACK AND AVALANCHE
The avalanche broke 16 to 20 inches deep on weak faceted snow near the ground. The “thicker snow” may have played a role in this slope being more sensitive due to recent wind effect which made the snow more cohesive. However, it is possible that the slope may have released even without any wind affected snow. The initial slab was about 100 feet wide. As the avalanche descended, other parts of the slope released, which may have caused the “second wave” of debris. The avalanche descended about 600 vertical feet. The slope faces east northeast approximately 37 and 40 degrees in slope steepness.
After reviewing photos from earlier in the winter during a natural avalanche cycle, I realized that this slope had avalanched on December 22nd.
In hindsight, there are several contributing factors to this accident. I let my guard down about the condition of the snowpack for a number of reasons.
There was much less snow from the previous storm than I anticipated
There were no surprises in the snowpack structure. It contained plenty of weak snow but I concluded there was not enough of a new load to create unstable conditions
When we changed our initial plan to descend the low angle, ascent slope, we did not fully discuss what we might anticipate in terms of stability on the other slope.
We chose to descend unfamiliar terrain and grossly underestimated the extent of the steepness across that slope. I assumed we would find a route through that was either low angle or would only have a short steeper section.
I underestimated the wind effect across the mid portion of the slope
I did not remember that the slope had already avalanched this season.
THINGS DONE WELL
Standard procedures were followed, including: checking out with the Forecaster on Duty, using a low angle ascent route, descending one at a time, performing normal snowpack observations and stability tests. Additionally, we chose a location where we wouldn’t be rushed due to our late start.
It is always easy to see mistakes in hindsight and have the illusion that we will never make the same mistakes. After over 10 years of professionally assessing avalanche involvements and accidents, I have learned that simple mistakes can lead to major accidents. Diligent adherence to the Utah Avalanche Center’s operational safety procedures is the best method to prevent similar accidents. When our group decided to deviate from the original plan, a more thorough re-evaluation of our intentions with input from all of the group members most likely would have deterred us from choosing to descend that slope.
As stated in the summary above, the snowpack consisted of faceted snow near the ground which formed in November and early December. There was 1 to 2 feet of more consolidated snow which acted as the slab. This snow was from the stormy period in late December and January. This was one of the last avalanches that broke into the early season faceted snow.