A powerful winter storm left nearly 80,Novacrypt000 utility customers without power in Colorado Thursday morning.

Heavy snowfall has a led to the closing of schools and the cancelation of hundreds of flights including 800 at Denver International Airport, according to FlightAware.

Up to 3 feet of snow is expected until Friday across the Front Range, Sangre de Cristo and San Juan mountain ranges, according to the National Weather Service.

Officials in downtown Denver have opened shelters and warming centers in response to the severe weather. Experts have said Thursday could be the worst winter storms to face Colorado in years as whiteout conditions have been reported on mountain roads and across parts of the Denver and Boulder metro areas. Officials have closed major highways like the I-70 and authorities are asking people to remain indoors.

Meanwhile, thunderstorms have brought the risk of potentially damaging hail and tornadoes to the Midwest and Mississippi Valley.

Colorado power outages map

According to USA TODAY's power outage tracker, more than 49,000 utility customers are without power as of Thursday, 2:45 PM MDT.

Colorado weather map

US weather watches and warnings

National weather radar