Blizzard conditions were reported at Denver International Airport this morning, causing United to cancel all flights until 5 p.m. Other flights were on hold.
Some flights were canceled at the Colorado Springs Airport, and Interstate 25 was closed between Colorado Springs and Denver.
Other closures are Interstate 70 between Aurora and Limon; U-S 85 from Ault to the Wyoming line; Colorado 93 near Rocky Flats from 64th Avenue and Colorado 72; Colorado 67 from Cripple Creek to Divide; and I-25 from Pueblo south to Trinidad.
Up to 30 inches of snow were expected in the foothills of the Front Range.
Xcel Energy reported 11-thousand customers were without power.
Allison Morgan of the state corrections department said its three facilities in the Denver area, Denver Reception, Denver Women and Camp George West were closed for weather for the first time ever.
Frank Benton of the National Weather Service said the storm will move out this evening and be followed by warmer weather.