Avalanche experts have a message for those planning to head into the high backcountry of Utah's mountains to take advantage of expected heavy snow over the next several days:
Unless you're a pro, don't do it.
The Utah Avalanche Center is forecasting dangerous avalanche conditions from tonight through Thanksgiving Day as a series of cold fronts and strong wind gusts move through the Wasatch Range, dropping up to several feet of snow in some of the most popular backcountry skiing and snowmobiling areas.
The storms will be accompanied by wind gusts of up to 80 miles per hour. The winds tend to blow snow into large drifts on north- and east-facing slopes, putting considerable pressure on the underlying snowpack and raising the likelihood of large slabs breaking free and barreling down the mountainside.
Heavy snowfall coupled with strong winds is always a recipe for hazardous conditions, especially when deposited on top of an underlying layer of older snow, said Bruce Tremper, director of the avalanche center.
"We're actually pretty lucky so far this year because the pre-existing snowpack is more stable than usual," Tremper said. "The main problem with this storm is there will be a lot of snow combined with a lot of wind."
Wind can deposit snow in a given area up to 10 times faster than regular snowfall, he said.
The danger should be highest at elevations above 8,000 feet, where a significant base of snow already exists underneath an icy crust. That means the largest danger zones will be in the Big and Little Cottonwood canyon areas, where many peaks top out above 11,000 feet.
Backcountry areas around Snowbasin and Powder Mountain are significantly lower in elevation, but Tremper said danger will still be high along ridgetops in those areas.
"It will still be good for a couple of feet up there, maybe more, depending on how it comes in," he said.
The avalanche center uses a five-level danger rating scale ranging from low to extreme. Conditions in the Wasatch, Bear River and Uinta ranges are currently rated at level 2, or moderate, but are expected to rise to level 4, or high, after today's storm.
The warning doesn't apply to slopes within ski resort boundaries where avalanche control is normally conducted, or to lower elevations where the existing snowpack is minimal.
While there have been no major accidents so far this season, Tremper said there have been some significant avalanches in the mountains east of Salt Lake City.
"A lot of people assume there's not enough snow for an avalanche, but there are always some accidents early in the season," he said. "It's a double whammy this time of year because people are so excited to come and get after it."
He said it takes more than an expert skier, snowboarder or snowmobiler to safely navigate the backcountry in such conditions -- people must also have expert-level avalanche training and experience, as well as locator beacons, shovels and other equipment in case of emergency.
"People need to realize if they are going to go into the backcountry, especially near the ridgetops, it's experts only or just don't go at all."
Before heading out, backcountry users are encouraged to check the latest conditions on the avalanche center's website, www.UtahAvalancheCenter.org, or call the avalanche hotline at 888-999-4019.
The storms may also result in some road closures. Updated information on closures is available through the Utah Department of Transportation at 801-975-4838.