The chain law was in effect for Molas and Red Mountain passes as of Thursday evening after the first major snowfall of the season hit higher elevations.
The Colorado Department of Transportation is reporting road conditions on U.S. Highway 550 headed north from Purgatory Resort as icy and snow-packed starting at Coal Bank Pass. Wolf Creek Pass on U.S. Highway 160 is reporting similar conditions.
From 8 a.m. to 4 p.m. Thursday, the weather service said 4 inches fell on Red Mountain Pass.
The Grand Junction Office of the National Weather Service is forecasting winter driving conditions throughout Thursday night.
Drivers should check road conditions before setting out Thursday night or Friday morning.