What could autumn snow mean for the winter? | ParkRecord.com

What could autumn snow mean for the winter?

Jeff Dempsey
The Park Record

September snow storms like the one that dusted the Wasatch Mountains Friday can be a potential issue; if the snow does not melt away, it makes for a weak base for the winter snowpack.

When a storm system moved into the Wasatch Mountains late this week, Evan Thayer was paying close attention. As the founder and forecaster at Wasatch Snow Forecast, he's spent the past six years tracking snowstorms in the Wasatch with an eye toward skiing. He said this late-September system caught his attention right away.

"This storm will be particularly wet as it is tapping into moisture from a Eastern Pacific hurricane (Hurricane Paine)," he said. "This will be accompanied by our coolest temperatures since April."

That means the potential for snow even at elevations as low as 7,000 feet, an uncommon occurrence this early in the fall.

"It is not unusual to see snowfall in September in the high elevations," he said. "Most Septembers feature at least one snowfall above 8,000 feet. However, the magnitude of this storm this early in the year is unusual. If the amounts of snow fall that we are currently expecting, it will be the type of storm we only see once every 10-20 years."

Significant snowfall in September could cause problems down the road depending on the weather in October. Mark Staples, director of the Utah Avalanche Center, said ideally, whatever snow falls this week will melt off entirely before the winter.

"[But] even if it does melt off it's good to start thinking about it now," he said. "What happens in the fall and early winter can potentially set the stage for the rest of the season. Because what we're doing is building the foundation for the snowpack. We're building a house and this is our foundation.

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"What that sits on is going to determine how well the house is built."

Staples said it's "never good" when snow starts trickling in early and sits on the ground a long time.

"The longer that snow sits on the ground, those snow crystals will become faceted," he said. "They change shape and become angular, they become sugary, weak crystals."

A base layer of faceted snow, with heavy winter snowfall packed on top, is a recipe for avalanches.

"The ideal scenario is we have no snow and a warm, dry fall, and then a switch is flipped and it starts snowing and doesn't stop," Staples said.

Staples said a dry autumn is good for everyone.

"We hope it melts away," he said. "I know everyone would be excited to have their mountain biking and trail running season extended. And from our standpoint, as far as having a stable snowpack, we'd like to see it melt off. But we will get other storms that will snow in the mountains and we hope that will melt off, too."

Even now, Staples added, it's never too early to start thinking about avalanche safety. He said he and his staff are heading to Colorado in October for a weeklong conference on avalanches, and classes for the public will start up soon, as well.

"We are starting to schedule classes already," he said. "We do a lot of free 'Know Before You Go' presentations. If there's any way to get people to put those on their radar, maybe think about taking a refresher course, that would be great. We could all use a little extra education."

For now, before avalanches are a concern, Thayer encouraged Summit County residents to get out and enjoy the snow if it falls.

"Aspen colors are approaching peak foliage and the new snowfall on these colorful groves of trees makes for some stunning scenery," he said. "If you’re willing to brave the cold, head out early on Saturday morning and bring your camera. I recommend Big Cottonwood Canyon!"

Wasatch Snow Forecast can be found at http://www.WasatchSnowForecast.com. For more information on the Utah Avalanche Center and to sign up for a class, visit http://www.UtahAvalancheCenter.org.

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