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JACKSON — Bridger-Teton National Forest avalanche forecaster Jim Springer got a ride to Rendezvous Bowl at Jackson Hole Mountain Resort this week and was greeted with a big surprise.

The Forest Service's snow depth meter, which measures up to 168 inches, was buried. Springer had to dig down a couple of inches to simply find it.

"There's just an incredible amount of snow up there," said Bob Comey, the director of the Bridger-Teton National Forest Avalanche Center.

With a winter snowpack still hanging into late April, it is setting up for a nice season of spring skiing.

But, as always, spring skiing can be dangerous, even fatal. Spring slides are always a major concern.

Already this season, numerous slides have been observed in Grand Teton National Park. Three weeks ago, skier Jimmy Chin rode an avalanche 2,000 vertical feet down Shadow Peak, but survived.

Last Monday, Grand Teton National Park rangers observed signs of avalanches while flying up the Garnet Canyon to Spalding Falls in a search for two skiers who went missing over the weekend.

"Most avalanches occur during and right after a storm," Comey said. "The other big thing is the sun is so warm, the warm-up is a big deal, especially the warm-up following a big storm. When it gets warm, stuff is going to fall down."

Skiing on spring corn snow, and avoiding avalanches, is a delicate line skiers and boarders balance in the backcountry.

The term "corn snow" comes from the kernels of snow that break off the surface of the snow when you apply your edges in a turn. These corn-sized melt-freeze snow kernels bounce down the slope ahead of a skier.

Corn snow forms when the sun shines on the spring snowpack and melts the surface during the day.

At night, if it freezes, the surface forms an eggshell crust, sometimes only inches thick.

As temperatures warm the following day, the snowpack gets heavy and wet slides can occur on steep slopes.

It is considered good etiquette to ski corn snow early in the day. Doing so late in the day chews up the terrain, which will freeze as big reefs overnight.

Teton Pass Ambassador Jay Pistono said most backcountry users ski the pass in the morning during the spring, but not all do.

"Trying to keep it smooth by people skiing it early in the morning doesn't always happen," he said. "I think that just reflects people's time schedules. But with the new equipment now, with wide snowboards and wide skis, it makes it easy to move over it."

Pistono, though, said it is best for all skiers and boarders if they skied the pass earlier in the day.

"If people could focus their efforts as far as keeping their late-day activities in a few areas so we don't chew up a lot of spots, that would be best," he said.

Last Tuesday, the Bridger-Teton Avalanche Center was forecasting a moderate avalanche danger. The avalanche center is to release its final advisory on Sunday, but experts warn that dangers will persist well into June at higher elevations.

"We can still have winter storms up at those elevations," Comey said.

He added that the snowpack at high elevations still resembles winter, not spring.

"We've got the deepest snowpack we've ever had," Comey said. "It's still a winter snowpack. It hasn't started to make the transition to spring. It's unusual to be this late in season and not have significant spring weather in mountains. We've had some rain and a little bit of warming. Our snowpack is so deep a lot of our instrumentation is buried."

Pistono estimates that more than 75,000 runs have been completed on Teton Pass this season. Countless more runs have been ripped off in Grand Teton National Park. They will surely continue for weeks, even months.

"As the winter snowpack transitions to a spring snowpack, there's going to be some hazard," Comey said.