A winter storm is expected to dump one to two feet of snow — and possibly more — in the Wasatch Mountains on Thursday and Friday, according to the National Weather Service. Commuters in the valleys could run into snow Friday morning.

And the Utah Avalanche Center is warning of high avalanche danger in the mountains of northern and central Utah through Monday.

By Thursday night, Utah Highway Patrol troopers were already feeling the impacts of the snow storm. An avalanche closed Provo Canyon, covering parts of UT-189 with 30 feet of snow. No people or vehicles were caught in the avalanche.

Shortly afterward, troopers were called out to a rockslide near Provo Canyon on UT-92 with several hundred-pound boulders blocking the road. Troopers said the rockslide was unrelated to the avalanche.

“Heavy rain is causing some serious issues in our canyons right now,” Utah Highway Patrol tweeted just after 8 p.m.

The NWS is forecasting that a southwest flow will bring heavy precipitation to the mountains through Thursday evening, when a switch to a northwest flow will affect Big and Little Cottonwood canyons. Wind gusts of 35-40 miles per hour are expected, and snow may fall at about two inches per hour at times, with accumulations of up to three feet possible in some areas.

The valleys will see mainly rain ahead of the cold front that will arrive Thursday night, with the precipitation switching over to snow by early Friday morning. And the snow “may impact the Friday morning commute.”

According to the Utah Avalanche Center, the danger in the backcountry will be high, “with both natural and human-triggered avalanches likely” because heavy snow and strong winds will create dangerous conditions. It advised avoid being on or beneath steep slopes. (The warning does not apply to ski areas where avalanche hazard reductions measures are taken.)