The chain-reaction crash began at 7:20 a.m. when a pickup pulling a trailer of snowmobiles hit a guardrail east of the reservoir, blocking traffic. Another truck was unable to stop in time and hit the first truck, according to the Utah Highway Patrol.
A man pulled over his van so that he and his 15-year-old son could avoid the crash and help the two truck drivers. But while the teenager was outside of the van, a fourth vehicle struck him. He was taken to a hospital with a broken leg.
Seven more vehicles then crashed into the slick accident scene, said Utah Highway Patrol Trooper Lawrence Hopper.
U.S. 189 reopened about 11:30 a.m.
The fog remained in the valleys for most of the day, with slight improvements in visibility as the day wore on.
The storm is expected to arrive in northern Utah by Sunday afternoon and last through Monday night, starting as valley rain and mountain snow until it all turns to snow Sunday night as the cold front passes. Meteorologists forecast the storm will bring 2 to 6 inches of snow to the valley floors and 5 to 10 inches to the mountains.
The storm will end the inversion,according to the National Weather Service in Salt Lake City. The cold temperatures and winds from the storm will scour out valley inversions, so the fog and haze should clear out and likely not return to any significant degree next week, according to the agency.
But until the storm passes the Utah Division of Air Quality still forecasts "red" air, or unhealthy breathability, for Salt Lake, Davis, Weber, Utah, Box Elder and Cache counties through Monday. Uintah and Duchesne counties were forecast for "yellow" or moderate breathability.
As the storm moves south, central and southern Utah might see precipitation Sunday and Monday, with the possibility of snow for central Utah.
The Utah Avalanche Center ranked the mountains in the Moab area as a "considerable" risk for dangerous snowslides Sunday. Meteorologists forecast 4 to 8 inches of fresh snow in the southern mountains, with the greatest amounts above 7,500 feet on south-facing slopes.
Every other mountain region in Utah was marked at a "moderate" risk for snowslides for Sunday.
Salt Lake City's high Sunday was 42 degrees, followed by an overnight low of 27 and a daytime high on Monday of 31 degrees; Ogden looked for 39, 25 and 29 degrees, respectively; Provo 42, 26 and 32; Logan 36, 17 and 26; Wendover 36, 20 and 30; Duchesne 35, 19 and 31; Cedar City 45, 26 and 34; St. George 56, 40 and 49; and Moab 42, 30 and 42 degrees.