By Keith Coffman
DENVER (Reuters) - A Mother's Day snowstorm blanketed the Northern Rockies on Sunday, prompting road closures in Colorado and Wyoming, and the same weather system prompted tornado watches in several Midwestern states as it moves eastward, officials said.
The National Weather Service issued winter storm warnings for large swaths of Colorado and Wyoming for Sunday through Monday morning, cautioning motorists about hazardous driving conditions.
"Gusty north winds up to 45 miles per hour over the plains of northeastern Colorado will produce areas of blowing snow and poor visibilities," the service said in an advisory.
In Wyoming, drifting snow from high winds forced the closure of a 150-mile (240-km) stretch of Interstate 80 from Cheyenne to Rawlins, the state's department of transportation said on its website.
Temperatures in Denver plummeted some 30 degrees overnight, and snow could accumulate on roadways throughout the region as they freeze, said Crystal Morgan, spokeswoman for the Colorado Department of Transportation.
Multiple accidents along Interstate 70 in the mountains 100 miles west of Denver forced the closure of the highway early Sunday afternoon, Morgan said, adding that Interstate 25 from Fort Collins to the Wyoming border was also closed due to adverse conditions and accidents.
Jim Kalina, a meteorologist with the National Weather Service in Boulder, Colorado, said the Denver metropolitan area could see up to 9 inches of snow and some mountain communities can expect accumulations of three feet.
"This is a slow-moving system and won't break down until mid-day Monday," Kalina said.
Kalina said parts of Nebraska, Iowa and Illinois are under tornado watches for Sunday afternoon as the system moves over the Plains states.
A spokeswoman for Denver International Airport said airline passengers are experiencing delays as aircraft needed to be de-iced before departing, but there were no reports of any flight cancellations.
The Denver Public Works Department said in a statement that it would deploy 70 snowplows overnight ahead of the morning commute.
(Editing by Scott Malone and Sandra Maler)