MOUNT OLYMPUS, Utah — The heat of May is starting to melt a lot of snow in Utah’s mountains. That’s filling waterways with very cold runoff.

The heat, and heavy rain last week, also loosened up snow that remained on steep slopes, and triggered an avalanche that came down in recent days in a popular hiking area.

“Wet avalanches are amazing the way they can come down,” said Mark Staples, director of the U.S. Forest Service Utah Avalanche Center.

We showed him our video of the avalanche from Chopper5.

Sometime during the last week, a massive, wet avalanche barreled down a narrow channel below the Mount Olympus face about a mile from the Neffs Canyon Trailhead. It appears, a large piece of rock and a large volume of snow broke away and ran down the channel sweeping up everything in its path.

“It’s like the chute on the back of a concrete mixer, funneling it down into the forest,” said Staples, describing the way the avalanche to debris wound down the mountain.

He said the slide likely came down last week after the big rainstorm.

 

“The snow is just saturated,” said Staples. “It loses all its strength, and it just comes rumbling down the mountain almost like a slug of concrete coming out of the truck.”

The avalanche snapped trees and moved large boulders. The slide appears to have run at least 1000 vertical feet, leaving a debris field a couple hundred yards long.

“Because the snow is so wet and dense, it’s more like concrete. It can knock over trees, and shape the landscape a little bit with more destructive power.”

In the winter, Staples said, the snow typically slides when extra weight is added on the snowpack, until it breaks. In the spring, with wet avalanches, the sun and rain weaken the snowpack.

“Until the snow pack can’t hold itself up anymore and then it comes sliding down,” Staples said.

Staples isn’t especially worried about people being caught up in any of these wet slides. But if you are in the back country and you’re still up in the snow zones, be especially cautious in the next few weeks for any snow sloughing off the mountains.

“These are the mountains,” he said. “This is Utah, the weather can be crazy. So, the main thing is: use common sense and look out for big dramatic changes in the weather.”