Big storm to wallop Utah Friday night

An intense winter snowstorm will sweep into Utah Friday night, causing hazardous driving conditions in valleys and possibly dumping more than a foot of snow in the Wasatch Mountains.

That will set up avalanche conditions similar to those of Nov. 13, when extreme skier Jamie Pierre, 38, was killed in an avalanche at Snowbird. Skiers should avoid the back country and stick to designated runs at resorts, according to Bruce Tremper, director of the U.S. Forest Service's Utah Avalanche Center.

The National Weather Service predicts the storm will hit northern Utah Friday about 6 p.m. and move into the Salt Lake Valley within an hour. It will bring three hours of intense snow, said Brian McInerney, hydrologist for the weather service. The storm should smack into the central part of the state by 10 p.m. and southern Utah later in the night. Wind gusts of up to 40 mph are forecast for west desert areas in advance of the cold front.

After the brunt of the storm moves through, snow showers will persist into Saturday from the Idaho line to Milford.

Snow totals for valley locations are forecast at one to three inches, while bench areas could get two to five inches, and northern mountains up to 15 inches, McInerney said.

After last weekend's storm blanketed the Wasatch with fresh powder, hundreds of people headed for resorts that were not yet open, according to Tremper. At least 12 human-triggered avalanches were reported in Little Cottonwood Canyon on Sunday. In addition to the slide that swept Pierre to his death, a skier at Alta suffered a broken leg after kicking off a slide beneath Gunsight.

Both resorts were closed then and no avalanche control work had been. As of Friday, they will be open with limited terrain.

"We always relax a little when the resorts open," Tremper said. "After that, you don't have that crazy factor."

Every year, skiers hiking up slopes at still-closed ski resorts present problems for rescuers, he said.

"At ski resorts, people get it in their brains that it's safe. But in the early season before avalanche control, you have a dangerous situation."

Sunday, the parking lot at Alta was practically full, he said. Many people who took to the slopes didn't practice techniques required for safety in the back country. "There was this mass hysteria, where people were behaving badly," he said.

As rescuers went to the aid of the injured skier below Gunsight, others above them were kicking off more slides that could have threatened them, he confirmed.

For the most part, skiers heading for the back country are well trained and well behaved, he said. But that isn't necessarily true of skiers who hike to terrain in resorts before they open.

And while Tremper expects the hysteria will subside, the avalanche danger will remain "considerable" — a three on a scale of one to five. That means human triggered avalanches are likely, he said.

Part of the problem is a weak layer of snow that becomes unstable with the weight of new snow on top of it. "It's what's called a persistent weak layer," Tremper said. "It can persist for a month or two."

Such weak layers are not uncommon in the early season. This year, however, is much worse than last.

"It's going to be the same song, second verse," he said of avalanche conditions this weekend. "It won't be quite as bad as last Sunday, but there will be hazardous conditions."

He warned back country skiers to avoid steep, north facing slopes above 9,500 feet. Unfortunately, that is where the deepest snow can be found.

"That's where the skiing is. That's the problem," he said. "This time of year, the conditions attract people to dangerous terrain."

csmart@sltrib.com —

From the archives

Read more about Jamie Pierre • http://bit.ly/stOXyJ

How avalanche victims fall into 'mental traps' • http://bit.ly/sPCcvp