By Jaime DeLage

St. Paul Pioneer Press

Black ice and blowing snow helped put a lot of cars in the ditch Monday night across Minnesota, according to the State Patrol.

More than 170 crashes were reported between 4 and 9 p.m., and more than 120 of them involved vehicles spun out or off the road, according to Lt. Tiffani Nielson. No serious injuries were reported. The cause in many cases was a combination of snow, high wind and icy-cold road surfaces.

The National Weather Service issued a Twitter statement urging metro drivers to slow down: “Roads may look clear but they are icy.”

The Minnesota Department of Transportation advised no travel overnight in southwestern Minnesota as visibility dropped to a half-mile or less.

Black ice, which isn’t really black but almost totally transparent, tends to form when the air temperature is warmer than the pavement and moisture freezes in a thin layer on the roadway, according to MnDOT. It often forms on overpasses and bridges.

Twin Cities temperatures warmed from around zero at noon to 7 degrees by 8 p.m. Monday before dropping again.

A wind chill advisory was issued for 3 a.m. to noon Tuesday. Below-zero morning temperatures were expected to pair with northwest winds of 10 to 20 mph to create wind chill values of 25 to 30 degrees below zero, according to the weather service.

Wednesday morning lows will be subzero again but the temperature is expected to rise to 17 degrees that afternoon.

Temperatures are expected to stay in the teens and 20s the rest of the week until it cools down to subzero lows again Saturday night.