Detailed Accident Report

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Date: 2008-02-15
Submitted By: CNFAIC
Place: Seattle Creek near Turnigan Pass
State: AK
Country: USA
Fatalities: 2
Summary: 4 snowmobilers caught and buried. 2 rescued, 2 killed.


February 16, 2008

Good morning backcountry travelers this is Carl Skustad with the Chugach National Forest Avalanche Information Center on Saturday, February 16th at 630 am. This notice will serve as a general backcountry avalanche advisory 5 days a week (Wednesday-Sunday) for the Turnagain Arm area, local variations always occur.

Weather Observations

In past 24 hours:

The Center Ridge weather station at 1800 feet in Turnagain Pass recorded 0 inches new snow. Total snowpack depth is 93 inches (1 inch less than yesterday). This weeks snow totals are 16 inches in Turnagain Pass and 23 inches at Alyeska. The temperature this morning is 17 deg F at Center Ridge.

Sunburst weather station at 3800 feet in Turnagain Pass recorded gale force winds mid week. Strong NE winds loaded leeward slopes this week. Winds subsided yesterday but are quickly increasing this morning with gust already in the 50?s. Ridge top temps are 8-11 deg F.

Snow has started falling again this morning. The radar and satalite images show heavy snowfall heading our way. Temps are forecasted to rise and snow will switch to rain this afternoon in coastal areas. Very strong NE winds are also associated with this storm front.

Bottom Line (Primary Avalanche Concerns)

The avalanche hazard will increase today as new snow and wind enters the area. Today natural and human triggered avalanches will be likely on steep alpine slopes in areas that receive heavy wind or new snow.

1. New snow loading wind slabs

2. The most recent layer of buried surface hoar that formed over the past two weeks. This weak layer is buried about 16-23 inches deep. This layer is fairly widespread in the Kenai and Chugach Mountains.

Avalanche and Snowpack Discussion (More detailed info?)

Yesterday an avalanche in the Seattle Creek drainage killed two snowmachiners. The large avalanche was triggered by the riders on a steep, leeward, loaded aspect under a cornice. Two other riders were dug out successfully by the remaining two members of the group. All riders where wearing beacons and had rescue gear. Without the quick rescue of the two surviving victims we would likely have had four fatalities. I will be riding to the site to do an assessment today.

Another very large human-triggered avalanche was reported on Magnum. Nobody was caught or injured in this avalanche. It was triggered remotely while a skier was digging a snow evaluation pit at the top of the West face above the highway. Preliminary reports called it a large class 3 small class 4 that propogated about 3000 feet across the slope. It was reported as 1 meter deep. Sounds like it failed on an "odd melt-freeze layer" that was older and deeper than the most recent layer of buried surface hoar. We will follow up and get more information on this avalanche as well.



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Turnagain Pass avalanche kills 2

SNOWMACHINERS: About 500 to 700 feet of the mountain collapsed.


Anchorage Daily News |

Published: February 16th, 2008 12:30 AM

Last Modified: February 16th, 2008 04:47 AM

Two snowmachiners died in an avalanche at Turnagain Pass late Friday afternoon, Alaska State Troopers said.

Troopers late Friday night identified the victims as Christoph Vonalvensleben, 25, and Jeremy Stark, 27, both of Anchorage.

The two were swept up in the slide and buried on a mountain above Seattle Creek north of Turnagain Pass near Mile 68 of the Seward Highway, said trooper spokeswoman Beth Ipsen. She said the victims were in a party of six snowmachiners who were highmarking and inadvertently triggered the avalanche after being out on the mountain for only about 10 minutes.

A third man, 38-year-old Andrew Baugh of Girdwood, was partially or fully buried but survived, Ipsen said.

The fatalities occurred hours after park officials and avalanche experts warned that 10 inches to a foot of new snow had created treacherous conditions in Southcentral's mountainous backcountry -- especially treacherous because the fresh snow would look great for snowboarding and snowmobiling.

Friends of the victims described them all as longtime Anchorage residents and experienced snowmachiners who often pushed the limits in backcountry.

"These guys ride three days a week. They knew the risks," said Jimmy Blaze, a longtime snowmachiner and friend of the victims who had talked by telephone with other members of the group.

"If they had to go, at least they went that way instead of some freak drunk-driving hit on the highway on the way home," he said. "They were doing what they love."

Blaze, who said he often snowmachines in Turnagain Pass, said the area of Friday's avalanche is known to be slide-prone.

Ipsen said an initial 911 call came in at 4:45 p.m. reporting the avalanche and that the slide may have swept over some people, Ipsen said.

There were about half a dozen friends skiing two bowls back from the parking lot when the avalanche occurred. Ipsen said about 500 to 700 feet of the mountain collapsed, leaving a swath of debris 200 feet wide.

Two other people were caught up in the slide but not buried.

All members of the snowmachining group reportedly had avalanche beacons, Ipsen said.

The other snowmachiners found the trapped people about 45 minutes after the slide, Ipsen said. They were dead.

A trooper helicopter flew to the scene Friday evening. The bodies were not recovered because conditions on the mountain were too risky, Ipsen said. Troopers will attempt to recover them this morning at first light.

"The area is a very popular area. Usually more experienced snowmachiners go out there," Ipsen said.

Conditions remain dangerous, Ipsen said.

Even before the latest snowfall, said Debra McGhan, executive director of the North America Outdoor Institute in Wasilla, conditions in the area were getting dicey, with Turnagain Pass and Hatcher Pass especially problematic.

"On Feb. 1," she reported, the institute's Dan Dryden "counted over 10 recent avalanches in Hatcher Pass. The avalanches were on all aspects -- north, south, east and west. He skied up the west ridge of Microdot (Mountain) and encountered shooting cracks, a clear marker of snowpack instability. He reported hearing whoomping of a collapsing weak layer at approximately 3,500 feet."

Upon digging a snow pit, Dryden found the situation worse. There were multiple layers of dense, compact snow sitting on layers of weak, unconsolidated snow. These are prime conditions for creating the kinds of avalanches that send automobile-size chunks of slab roaring downhill.

"(And) now we have several new inches of snow as the icing on top of this mixture," McGhan said in an e-mail. "In layman terms, this is a lasagna recipe for avalanche. The (loose) depth hoar acts like ball bearings, and all it takes is a simple trigger like ... a snowboarder, skier or snowmachine to rip it loose and put everything in its path in peril."

McGhan said anyone planning to recreate this weekend needs to be especially careful. She noted there have been more than 50 avalanche victims in the state in the past decade.

The Chugach National Forest Avalanche Center is warning not only of the risks of human-triggered avalanches but of dangers of people being caught in runout areas by naturally occurring avalanches. The Turnagain Pass area has the same layer-cake problem that Hatcher Pass has.

Wind slabs, Chugach avalanche officials report, have formed "over the most recent layer of buried surface hoar that formed over the past two weeks (of cold). The weak layer is buried about 16 to 23 inches deep. This layer is fairly widespread in the Kenai and Chugach mountains. Two other weak layers of buried surface hoar exist in isolated pockets approximately three to four feet down and four to six feet down."

An avalanche triggered at such depths would likely be massive, but even a slide going only a foot deep can easily bury and kill someone.

Closer to Anchorage, conditions are equally dangerous in Chugach State Park, officials said.