The National Weather Service Thursday forecast additional snowfall for parts of Colorado blanketed by 10 inches to 20 inches of fall snow.

NWS spokesman Kyle Fredin said Denver could see as much as eight additional inches, while nearly an inch of snow per hour was expected in Boulder and Jefferson counties, The Denver Post reported.

The snowstorm that hit the Wyoming and Colorado Rockies this week left more than 3 feet of snow in some areas, AccuWeather.com said.

The snowfall prompted interstate closures in both states, along with parts of western Nebraska. Travel is dangerous as high winds and blizzard conditions have significantly reduced visibility and increased the risk of mountainous drifts, AccuWeather.com said.

Frontier Airlines canceled 19 flights and announced three-to-four hour delays at Denver International Airport due to the inclement weather. Airport officials said crews have been unable to keep runways and taxiways consistently clear of snow.