DES MOINES, Iowa (AP) -- A fast-moving storm system dropped both snow and rain over portions of the Midwest on Wednesday, packing strong winds that flipped semitrailers, damaged industrial park buildings and downed power lines in parts of Iowa and Nebraska.
National Weather Service officials said the system, which began Tuesday around Utah and moved eastward into the country's midsection, dumped more than a foot of snow on the Rockies before creating conditions ripe for tornadoes. But they said the weather wasn't quite as warm as it could have been, so the threat decreased.
"Probably the worst has passed," said Stephen Corfidi, a meteorologist at the Storm Prediction Center in Norman, Oklahoma.
By Wednesday night, remnants of the system were reported in eastern Iowa, northeast Missouri and western Illinois. Winds between 25 and 35 mph were expected into early Thursday, with wind gusts of up to 60 mph in some spots.
Corfidi called the system a "classic mid-November storm."
"Basically there's a warm side and a cold side to these systems, and the unifying threat is a very strong wind field all the way around it," he said. "So on the cold side, you have a chance for snow or freezing precipitation accompanied by very strong winds and occasionally blizzard conditions. ... On the warm side, the thunderstorms that grow in the strong wind environment tend to rotate. And if they rotate long enough, and if the moisture is great enough, they can produce tornadoes.
"So usually you kind of get a one-two punch with this type of event."
Portions of Utah, New Mexico, Wyoming, Colorado, Nebraska and Kansas saw blizzard-like conditions. Some of those same states and others were hit with thunderstorms as well.
Authorities on Wednesday received reports of damage to buildings in southwest Iowa, flipped semitrailers on Interstate 80 in western Iowa and power outages in central Iowa.
"The driver says all he remembers is a dark cloud," Iowa State Patrol Sgt. Mike Wesack said about a semitrailer that flipped just west of Avoca. "Next thing he knows, (the vehicle) was on its side on the (other) lane."
Kara Kelly, a regional spokeswoman with the American Red Cross Serving Greater Iowa, said the agency was assisting residents in Melrose, Knoxville and Des Moines in central and southern Iowa.
Officials were investigating several possible tornadoes in Iowa and severe weather with similar potential in Nebraska, but they said the reports could not be verified until survey teams examined any damage.
At one point, a tornado watch including sections of Nebraska, Iowa, Kansas and Missouri had been issued.Weather officials eventually downgraded the threat and issued various severe weather warnings for south-central Iowa and northern Missouri. The system was expected to bring high winds to portions of Illinois and Wisconsin during the overnight hours.
The system had been expected to affect more than 36.5 million people from Colorado through Ohio, and from Texas north through Michigan. It dropped up to about 5 inches in parts of the Denver area on Wednesday, and Colorado highway patrol troopers reported several crashes north of the city on windy, icy Interstate 25 near the Wyoming border before the sun came out. Wyoming authorities also shut down large sections of roadways.
The Nebraska State Patrol reported several minor accidents involving vehicles sliding off icy or slushy roadways, but no injuries were reported.
Alan Salyards said truckers coming through his Flying J Travel Plaza near Big Springs, a Nebraska town along the Colorado border, didn't seem especially concerned. He said plow trucks were working all morning to keep the roads passable.
"The drivers are just doing their normal thing," he said.