Avalanche Accident Report         

Forest Service Utah Avalanche Center (in Logan)

Tony Grove Lake Accident – Snowboarder caught in wet avalanche, carried, and injured on Saturday, April 26, 2008

Accident site investigated by Toby Weed and Darren McAvoy on April 28, report by Toby Weed.

Location: 41˚53’42.10”N 111˚38’47.05 W….. The wet point-release avalanche was on a very steep northeast facing slope at around 8,200’ in elevation slope just above the northwest shore of Tony Grove Lake in the Logan Ranger District of the Wasatch-Cache-Uinta National Forest.

Accident and Rescue Summary:

32-year-old Snowboarder Jen Swanson, mother of three from Cache Valley Utah, was injured after she triggered a loose wet avalanche on a very steep slope and was caught and carried into trees below. Jen and husband, Cory Swanson used a snowmobile to access the Tony Grove Lake Area and were taking turns shuttling the sled, filming, and riding the short but extremely steep slopes directly north and west of the Lake.

Just before her accident, while Jen videoed from below, Cory successfully dropped into and rode out a line just to the west of the accident site, but in so doing, he triggered a small wet avalanche that harmlessly followed him down slope. With Cory at the camera, Jen dropped into the line, and after a few high-speed turns on an increasingly steep roll over, triggered a small wet avalanche. Shallow but heavy snow picked up speed and overwhelmed her, knocking her off her intended course and board-first into the first tree. The small but fast moving avalanche and the speed of the fall swept her further down the slope and backwards into the second tree. When the avalanche came to a stop, she was on top of the shallow debris and conscious.

After assisting and stabilizing Jen, Cory had to ride his snowmobile a couple miles and 2000 vertical feet to the summit of Naomi Peak for Cell phone coverage to call for help. Luckily, both members of the Cache County Sheriff’s volunteer Search and Rescue team and a medical helicopter were in the Tony Grove Area shortly after another rescue, and were quickly able to get to and evacuate Jen. She suffered ankle and back injuries including a few fractures, but is expected to fully recover quickly…She considers herself very lucky to have survived and not to have been much more seriously injured by the accident.

Terrain Summary:

The avalanche, on a 45˚to 50˚ steep slope near vertical cliffs just above Tony Grove Lake, occurred in a very popular area commonly accessed in the winter by a 7-mile snowmobile ride up the Tony Grove Road from trailhead parking off Utah Highway 89 in Logan Canyon. The avalanche ran no more than 200 vertical feet before stopping near a popular summer trail that traverses around the Lake.

Avalanche Data: 

The small wet avalanche should be classified as a WL-AS-R1-D1. It started the width of a snowboard turn, (<20’) and fanned out to be about 70’ wide and a foot deep in two piles at the base of the slope after running around 200 vertical feet. The old melted and then refrozen snow that was the bed surface of the avalanche was quite dusty or off colored (brownish) from a pre-frontal wind event, which deposited airborne dust , a week prior to the accident on April 19^th.

Weather and Avalanche History: 

The avalanche involved fresh snow from a storm on April 24^th, and a Snotel site within a mile of the site recorded a little over an inch of water equivalent gain. On the day of the accident this had settled out into around 6 inches of 2-day-old snow sitting on a warm and dusty old snow surface. It was a sunny day and the temperatures recorded at the nearby Snotel site climbed from 34˚F at noon to 37˚F at 1:00, near the time of the accident. Solar warming caused the fresh snow to melt and become slushy and sticky, snow conditions which are prone to avalanching.

Comments:

This case shows that even the little ones can hurt you in the wrong terrain. Jen and Cory understand the potential consequences of riding on extremely steep slopes. They carried proper avalanche rescue equipment, and used safe travel protocols by only exposing one at a time to avalanche danger. The avalanche Cory triggered initially might have been taken as a clue that other similar avalanches were likely, but Jen was confident that she could out ride or ride through any possible fresh snow slide. The speed and force of the heavy snow in the small wet avalanche were clearly unexpected, and we should remember that one way avalanches kill is traumatically.

Photos and Videos:

Video posted on YouTube of the accident and rescue

Photos taken of the site on 4-28-08