UPDATE: I-15 northbound near Nephi in Juab County has reopened, according to a tweet from the Utah Department of Transportation.
The freeway was closed earlier 1 mile south of Nephi. Utah Highway Patrol reported multiple accidents there.
Although the freeway has reopened, delays remain, KSL Newsradio reported.
Also, the National Weather Service extended the Winter Storm Warnings for the Salt Lake and Tooele valleys, Utah County, and the Wasatch Mountains south of I-80 through 9 a.m. Tuesday.
Earlier: SALT LAKE CITY — Amid an unusually warm and dry Utah winter, a snowstorm pounded the Wasatch Front on Monday.
The late-night and early morning blizzard snarled traffic and caused delays during the Presidents Day commute and persisted into the afternoon as crashes continued to stack up.
Between midnight and 11 a.m., Utah Highway Patrol reported 217 crashes throughout Utah streets and highways, with 60 still waiting for troopers or officers to respond about noon Monday.
Of those crashes, four involved UHP trooper vehicles, though no troopers were hurt, UHP reported. Any injuries in other crashes were minor.
The National Weather Service issued a winter storm warning along the I-15 corridor, warning of heavy snow until 9 p.m. Monday in areas including the Sanpete and Sevier valleys, west-central Utah and southwest Utah.
As of 10 a.m., the agency reported 5 inches of snow at the Salt Lake City International Airport. More than a foot of snow was reported in the Wasatch Mountains at ski resort areas including Brighton Crest, with 16 inches, Alta Collins, with 14 inches, and Snowbird, with 13 inches.
The agency urged commuters to use caution while driving, reporting slick roads and clouded visibility throughout the state.
"While snow will become more intermittent in northern Utah as the day progresses, periods of heavier snow are still possible," the weather service said in a tweet.
The slick and snowy roads contributed to dozens of crashes along Utah highways and streets, and it slowed some roads to a crawl. Westbound I-80 was shut down at 1300 East in Salt Lake City due to multiple crashes, the Utah Department of Transportation reported about 11 a.m., urging drivers to plan for delays and alternate routes.
Multiple crashes and slide-offs also backed up traffic for miles up Big and Little Cottonwood canyons as skiers and snowboarders headed to the slopes for the fresh powder. Both canyons closed at 10:45 a.m. for snow plows, but were opened again by noon.
"It’ll be a journey today," Unified Police tweeted. "Lots of snow and heavy congestion."
The Utah Avalanche Center also warned of high avalanche danger near Logan, Salt Lake City, Provo and Skyline, and considerable danger near Ogden and in the Uinta Mountains.
As of Monday afternoon, 43 flights were delayed at the Salt Lake City International airport, spokeswoman Nancy Volmer said. Planes were leaving their gates on time but were delayed because they needed to be de-iced, she said.
As of about 11 a.m., about 3,900 customers in the Salt Lake metro area were without power, including about 2,300 in Taylorsville, said Rocky Mountain Power spokesman Dave Eskelsen.
Earlier Monday, about 7,000 customers had lost power due to the weather, including 4,500 in Salt Lake County and 2,000 in Davis County, Eskelsen said, but many had been restored by the afternoon.
"Crews have been working really hard since late last night, and they’ll keep at it until everything’s restored," Eskelsen said, thanking customers for their patience.
The National Weather Service projected snow accumulations of 8 to 14 inches in the Wasatch Mountain valleys, Wasatch Mountains south of I-80, the western Uinta Mountains and the Wasatch Plateau by about 4 p.m.
The Salt Lake and Tooele valleys were expected to have accumulations of about 1 to 3 inches, with snow falling until about noon.
The storm comes amid an unusually dry and warm winter in Utah, but temperatures were projected to dip this week, with lows expected to reach about 19 degrees in the Salt Lake area Monday night. Tuesday was expected to reach a high of 27 degrees and a low of 14 degrees.
Check traffic conditions on the KSL Traffic Page and get a complete weather forecast here.
Contributing: Shara Park