Avalanche forecasters have released their preliminary report on a deadly avalanche near Whittier which buried an Anchorage man Wednesday.

The Chugach National Forest Avalanche Information Center posted its overview of the Blackstone Glacier slide "with heavy hearts," following 41-year-old Chad Christman's death Wednesday afternoon. A GoFundMe account set up for his family had raised more than $5,000 by Friday.

“Our thoughts go out to the family, friends and riding partners at this difficult time,” forecasters wrote.

Anchorage snowmachiner Chad Christman, 41, was killed in a Blackstone Glacier avalanche on Wednesday, May 2, 2018. (Credit: Stefanie Suydam)

Alaska State Troopers had previously said the slide, on the upper glacier, was reported to them at about 3:40 p.m. Wednesday. Troopers initially reported that six snowmachiners from a group of nearly 20 were caught in the avalanche, but the center’s report mentioned only three.

“One rider was partially buried, one successfully deployed an airbag and came to rest on the surface and one rider was fully buried (except for a hand breaking the surface) and killed,” forecasters wrote. “The victim’s party was able to establish an airway and begin CPR within five minutes of the avalanche.”

An avalanche Wednesday, May 2, 2018 on the upper Blackstone Glacier near Whittier killed Anchorage snowmachiner Chad Christman, 41. (Credit: Courtesy Koltan Lucas)

Photos of the avalanche’s aftermath, from snowmachiner Koltan Lucas, show searchers digging through snow at the base of the avalanche chute.

A fatal avalanche Wednesday, May 2, 2018 on the upper Blackstone Glacier near Whittier. (Credit: Courtesy Koltan Lucas)

The avalanche center estimated the slide, which was funneled into a gully on a northeast-facing slope, at a crown depth of 2 to 4 feet, up to 300 feet wide and descending about 1,000 feet on the 5,000-foot slope.

“The debris was enough to bury a car, destroy a small building or break several trees,” forecasters wrote.

Forecaster Wendy Wagner said Friday that the report was based on interviews with the surviving snowmachiners from a group of “riding partners.” Just four riders from the larger party were in the area when the avalanche occurred, one of whom wasn’t buried by the avalanche at all.

“We have been able to determine that this was human triggered – it was triggered by the group,” Wagner said. “We don’t know how or in what way that happened.”

Staff from the center haven’t yet visited the site of the avalanche, Wagner said, but plan to conduct more interviews and investigation before issuing a final report. In the meantime, with the center shut down for the season at the end of April, she urged Alaskans to be alert to the possibility of similar slides amid potentially unstable conditions.

“These springtime avalanches can be unique; they can also be very predictable,” Wagner said. “It’s the time of year where if you get a winter snowstorm like we were having in late April, and then it’s May and the sun comes out, the sun can have a major impact through warming.”

Although the avalanche center is closed for the season, forecasters urged anyone traveling in potentially avalanche-prone areas to consider a series of springtime safety tips posted on its advisories page. Those tips include watching for red flags of avalanche activity, such as recent avalanches, cracks in snow, new snow, wind loading and rapid warming.

Melissa Frey contributed information to this story.

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