Wet roads, fresh falling snow and dropping temperatures combined Friday night to make for a slick drive in the Denver metro area.

Aurora, Centennial, Thornton and parts of south Denver went on accident alert late Friday. Drivers involved in accidents, without injuries, could exchange insurance information and leave the scene without waiting for police to arrive.

Multiple accidents were reported in the Denver area as the temperature dropped to below freezing, in the upper 20s, after 8 p.m., with light snow and fog. The wind chill brought the temperature down to about 13 degrees, according to the National Weather Service.

The wet, frigid weather system in northeastern Colorado Friday night was forecast to drop up to 2 inches of snow in the Denver area Friday afternoon and evening and between 10 and 20 inches in the northern mountains.

Unlike recent Colorado storms originating from the southwest in which rain fell for several hours before turning to snow, the transition from rain to snow could happen quickly Friday because this storm is coming from Wyoming.

Snow began falling after 3 p.m. in Denver.

“The storm is currently moving through the northern Rockies,” said Scott Entrekin, meteorologist for the National Weather Service in Boulder. “There’s a lot cooler air.”

From around 10 a.m. to 11 a.m., temperatures in Denver dropped almost 20 degrees, said forecaster David Barjenbruch.

“The cold front that’s moving through is packing a punch today,” he said.

Denver residents could see anywhere from a dusting to about 2 inches of snow, Barjenbruch said. These showers are likely to continue into the evening commute and could make roads slick when the sun goes down and ice begins to form on the roadways, Barjenbruch said.

The snow is expected to decrease overnight, Barjenbruch said.

The mountains will receive a more hefty snow dump, Barjenbruch said.

The westbound lanes of Interstate 70 closed for more than two hours from C-470 to Silverthorne on Friday because of adverse conditions and multiple accidents, but had reopened by 6 p.m.

U.S. 6 over Loveland Pass also closed due to adverse conditions at 11:10 a.m.

After getting anywhere from 4 to 8 inches of snow in northwestern Colorado near Rabbit Ears Pass Thursday night and early Friday, up to 20 inches of snow could fall in the northern mountains Friday, Entrekin said.

The central mountains could get between 6 and 12 inches of new snow Friday, but the southern mountains aren’t expected to get much accumulation, he said.

On Saturday, the high temperatures will be in the 30s or 40s and hit 52 degrees by Sunday.

The next storm system could bring snow to the Denver metro area by Wednesday evening, making driving trickier for holiday traveling.

“It definitely bears watching closely,” Entrekin said.

Kirk Mitchell: 303-954-1206, kmitchell@denverpost.com or @kirkmitchell or denverpost.com/coldcases