By Keith Coffman
DENVER (Reuters) - A blizzard of "historic proportions" that hit the U.S. Rocky Mountain and Plains states this week was moving eastward on Thursday as it weakened, hurling hurricane-force winds, tornadoes and heavy rain on its way, weather officials said.
"While the storm has reached its lowest pressure and will gradually weaken over the next few days, strong winds will continue on the west side of the storm across portions of the Central and Northern Plains," Bob Oravec, a meteorologist with the National Weather Service (NWS), said on Thursday in a weather advisory.
A day earlier, the NWS had described the blizzard - previously dubbed a "bomb cyclone" by U.S. meteorologists for its quick, late season punch - as being of "historic proportions" in a post on Twitter. Hurricane-force winds involve frequent gusts or sustained winds of more than 74 miles per hour.
The blizzard, bringing severe snowfall, poor visibility and powerful winds, caused hundreds of flight cancellations and thousands of power outages in Colorado and Texas. It was expected to unleash similar conditions over areas in Colorado, Wyoming, Nebraska, South Dakota and North Dakota before moving into northwest Minnesota, Oravec said.
A state of emergency was still in effect in Colorado as cities and towns dug out from the storm, during which strong, 70-mile-per-hour wind gusts pushed tractor trailers sidewise and left up to two feet of snow in some areas.
In parts of Arkansas, Mississippi, Missouri and Tennessee, tornado watches were issued until Thursday afternoon. Tornado warnings were also issued in parts of Illinois, Kentucky, Ohio and Indiana.
An AccuWeather meteorologist said on Thursday on Twitter that at least one tornado had formed near Evansville, Indiana.
The storm also caused flash flooding across the Plains and Midwest states, the NWS reported. Residents in Norfolk, Nebraska, were issued evacuation orders on Wednesday after the Spencer Dam at the Niobrara River was reported to have failed, according to the Lincoln Journal Star newspaper.
Some flights resumed on Thursday at Denver International Airport and flight cancellations were down to more than 600 on Thursday, from more than 1,300 in the region a day earlier, according to FlightAware.com.
Power outages in Colorado affected about 80,000 homes and businesses, down by 8,000. About 60,000 in Texas also experienced outages on Thursday morning, dropping by 17,000.
The storm was blamed for the death of a Colorado state trooper, who was hit by a car that slid on ice on the highway as he was attending to a car wreck.
Schools and government offices remained closed Thursday across the region.
Remnants of the snow fall and rain would clear from Denver and the mountain and plains areas by midday, he said.
(Reporting by Keith Coffman in Denver; writing and additional reporting by Rich McKay in Atlanta and Gina Cherelus in New York; Editing by Bernadette Baum)