Detailed Accident Report
Submitted By: Utah Avalanche Center; Bruce Tremper
Place: Gobbler's Knob Area
Summary: unknown number caught, 1 buried and killed
***OFFICIAL REPORT FROM UAC***
**For more information and images; visit:
Forest Service Utah Avalanche Center
Date: February 16, 2003 FOR IMMEDIATE RELEASE
Contact: Bruce Tremper 801-231-4744
Avalanche Fatality in Salt Lake Area Mountains
This morning, Bruce Tremper, Director of the Forest Service Utah Avalanche Center visited the site of an avalanche fatality yesterday on Gobbler?s
Knob, which is in Mill Creek Canyon near the ridge between Big Cottonwood Canyon and Mill Creek Canyon.
A group of backcountry skiers triggered an avalanche at an elevation of about 10,100 feet on a steep (40 degree), north-northwest-facing slope. One
skier was caught and carried by the avalanche 1500 vertical feet. The slab avalanche was one foot deep and 100 feet wide, but after descending a short
distance, it broke out additional slabs on either side, making an avalanche over 300 feet wide. This large volume of snow funneled into a narrow gully and
traveled a long distance, burying the skier about four feet deep.
The avalanche conditions yesterday were not particularly dangerous throughout most of northern Utah. Hundreds of backcountry skiers, snowmobilers,
snowboarders and snowshoers have been able to negotiate most steep slopes without incident this past weekend. The Forest Service Utah Avalanche
Center rated the danger on this type of terrain as ?moderate?, which is a level 2 on a scale of 1-5 (low, moderate, considerable, high and extreme).
Moderate danger means that human triggered avalanches are possible, but they are localized, instead of being more widespread. Statistically, most human
triggered avalanches occur in terrain rated as either ?moderate? or ?considerable?, because the snowpack is safe enough for people to negotiate many
slopes, but there are just enough booby traps lurking, which people can trigger.
The avalanche was triggered in a steep, rocky area with a thin, weak snowpack. Two different culprit weak layers formed within the snowpack during
clear weather in December and again in January. During periods of clear weather, large ?temperature gradients? can develop within the snowpack, which
metamorphose the snow into very weak, sugary ?faceted? snow crystals. Once buried, they are notoriously persistent and continue to produce avalanches
each time a storm adds additional weight on top of these buried weak layers, especially in thin snowpack areas.
Counter intuitively, drought years, like this season, are usually much more dangerous than years with copious amounts of snow. Thin snowpacks are very
weak and each additional load of new snow or wind-blown snow can easily over load the buried layers of weak, faceted snow. Thick snow is generally
strong enough to support the additional weight, but thin snow is especially vulnerable.
For more information on avalanches, please feel free to call our staff or visit the web site listed below.
Bruce Tremper, Director
Forest Service Utah Avalanche Center
801-524-5304 Forecast Office (4 am to noon daily)
Main web site: www.avalanche.org
Media Packet: www.avalanche.org
List of avalanches: www.avalanche.org
Photos of recent avalanches: www.avalanche.org
Fierce Storm Adds to Avalanche Risk
BY KEVIN CANTERA
THE SALT LAKE TRIBUNE
One day after a Salt Lake County man died in a backcountry
avalanche on the Wasatch Range, safety officials warned that
Sunday's weather could raise the likelihood of further snow slides.
Allan Davis, 48, was swept away and buried Saturday evening when
a 100-foot wide swath of unstable snow broke away from the
northwest face of Gobbler's Knob, a 10,400-foot ridge between
Porter Fork and Alexander Basin in Mill Creek Canyon.
Davis, one of a group of five skiers, was buried beneath about 5
feet of snow in the 5:30 p.m. avalanche, said Salt Lake County
sheriff's Deputy Peggy Faulkner.
His companions, two men and two women who were not injured in the slide, freed Davis from the snow
and called for help on a cell phone, Faulkner said. A medical helicopter dropped a team of rescuers into the
area, where they were able to find the survivors, who already had determined that their companion was dead.
Davis was an expert skier and a backcountry wizard well aware of the dangers of the mountains, said
Bruce Tremper, director of the U.S. Forest Service's Utah Avalanche Center.
"He was just an amazing guy" who often had volunteered his time to help avalanche forecasters distribute
information, Tremper said. "There were only a few localized places where people could trigger an avalanche
and they just happened to find one. . . . It makes me pretty sad."
In fact, the entire group was well prepared for the treacherous winter conditions of the mountain
hinterlands, Faulkner said.
"They were wearing [locator] beacons, and they really watched closely for any sign of instability. They
were just unable to predict what was coming," Faulkner said. "It does demonstrate how dangerous it can be
Search and rescue personnel guided the four survivors, who were not identified, out of the backcountry
early Sunday, a few hours before Davis' body was recovered by deputies, Faulkner said.
Davis was the first person killed from injuries suffered during a snowslide in a winter season that has
seen more than 90 Wasatch Range avalanches unintentionally triggered by skiers, snowboarders or
snowmobilers since Nov. 8, according to a report from the Utah Avalanche Center.
"We had 63 unintentional, human-triggered [avalanches] in three weeks in January. I'm sure we set some
kind of record," Tremper said.
Another 60 or so snow slides have been intentionally triggered, or occurred naturally since November.
In Saturday's slide, a hard slab of snow and ice between 1 and 2 feet deep broke away from the mountain
at an elevation of about 10,100 feet and roared nearly 1,600 feet down the steep slope, tearing up trees and
brush. The slide fanned out to a width of nearly 350 feet in places, and debris piled up "funneled into a
narrow gully," said Tremper, who examined the slide area Sunday.
"It started out as a relatively small slide [but] it soon involved an entire bowl below the ridge and picked
up a large volume of snow," he said.
A Pacific storm front that rolled onto the Wasatch Front on Sunday, changing rain to snow and bringing
wind gusts close to 70 mph, had forecasters predicting further instability.
High winds tend to distribute snow in dense and inconsistent drifts along terrain features, and fresh, wet
snow typically does not bond well to older snowpacks, which are often slick and icy on the surface.
Because the Wasatch Mountains have received a relatively light blanket of snow this winter, the peaks are
abnormally vulnerable to anything -- human or otherwise -- that can trigger a slide.
"Drought years are especially dangerous," Tremper said. "A thick snowpack is quite stable. In a drought
year the snowpack is thin, and thin snow is weak snow."
Anyone planning to venture into the mountain backcountry is urged to first check for avalanche
advisories, which are available by calling 801-364-1581, or on the Internet at www.