Avalanche expert explains how to measure slope angles

BIG COTTONWOOD CANYON — Experts are advising Utahns to stick to slopes that are 30 degrees or less while avalanche danger remains high in most of the state’s canyons.

“We’re coming off the heels of this remarkable storm and this dense, heavy, wind-driven snow all fell on a layer of weak, sugary snow that developed during our mid-December dry spell,” Utah Avalanche Center forecaster Craig Gordon said.

He said the period for natural avalanches to occur following our most recent storms has passed.

“The snow now waits for a trigger like us to roll along, knock the legs out from underneath it and once we do, we’re staring down the barrel of a very dangerous avalanche,” Gordon said.

To avoid slides, experts like Gordon said it’s best to stick to certain slopes.

“Thirty degrees and less steep, it’s kind of the magic number,” he said.

No need to bring a protractor. Gordon said there are several tools people can use in the outdoors to figure out how steep a slope is.

He has a clinometer. Gordon holds it up to the horizon of the slope to see the slope angle. He said it only measures one piece of terrain.

“I don’t want any steep slopes above or adjacent to me,” Gordon said.

He said it’s easy for humans to trigger slopes that crash down like a roof.

“It’s like pulling the log out from the bottom of the wood pile and now the entire wood pile is crashing down on top of me,” Gordon said.

To survey a large area, he recommends using phone apps, like on X.

“I’m going to match my terrain choices with what the avalanche danger is,” Gordon said. “When it comes to slope angle, if I go to my mapping program and hit my slope angle option, I’ll have different shading options that shows me what my sloping angle is.”

Gordon said the phone apps are best used ahead of time, before deciding where to go.

“There’s lots of room for error and interpretation,” he said.

He recommends using all of the available tools together to make an informed decision. Gordon said people should always check their local avalanche forecast before heading out.

Gordon said before deciding where to go, take into account the weather, snowpack, and terrain.

“I want to avoid any terrain traps,” he said. “Those could be gulleys, trees that I could get stranded in, that could be a river bottom.”

He said doing so can save lives.

“Once we get into that elevated avalanche danger category, It’s time to be very cognizant of our surroundings, and what kind of terrain is above us, what kind of terrain we’re connected to,” Gordon said.