Strong thunderstorms are expected in southeast Kansas and southwest Missouri with a chance for hail and high winds.
The National Weather Service says the spring storm system is moving into the southern Plains later Tuesday, spreading eastward from Oklahoma into southeast Kansas and into the western section of the Missouri Ozarks by Tuesday evening.
The weather service in Springfield says there's also a chance for damaging winds and large hail and possibly tornadoes in the area. Temperatures could drop near the freezing mark, particularly by Thursday and early Friday.
Heavy rainfall and flash flooding are also expected, with the brunt of the heavy storm likely ending early Wednesday. The weather service also says additional storms could hit the area through the weekend.
A large spring snowstorm delivering heavy snow, high winds and rain was causing travel problems from Wyoming to Chicago on Tuesday.
In Wyoming, some big stretches of Interstates 25 and 80 have reopened, but snow and blowing conditions were still making driving dangerous along the interstates and smaller highways.
Meanwhile, freezing rain, snow and strong winds, were hitting Kansas and South Dakota, where numerous local elections were postponed. Some schools in Minnesota dismissed students early as travel conditions deteriorated.
Snow in the Denver area has been lighter than expected but around 500 flights have been cancelled at Denver International Airport and deicing was delaying departures.
Flights bound for Chicago's O'Hare International Airport, meanwhile, were being delayed an average of nearly four hours because of dense fog.
Tornadoes were also possible in parts of Texas, Oklahoma and Arkansas later in the day.
While April snowstorms aren't unusual in Wyoming and the Rocky Mountain West, the storm comes after a rather tame winter in many areas.
"We haven't really had bad days like today where everybody is stuck and nobody can go anywhere," Sam Blaney, who was working the service counter at the Petro truck stop in Laramie, said.
About two dozen truckers and other motorists took refuge at the truck stop to wait out the storm, Blaney said.
Lander has gotten more than a foot of snow so far. In Pine Bluffs, near the Nebraska border, wind has created 1- to 2- foot drifts out of the snow that has fallen there.
"I'm pretty confident that this particular storm is more widespread and has caused more travel problems and closures than any storm we've had this calendar year certainly," Bruce Burrows, spokesman for the Wyoming Department of Transportation, said.
As the storm moved into Colorado Monday night, two tornadoes were reported near Akron on eastern Colorado's plains though forecasters haven't confirmed the twisters yet. A trailer home rolled over onto its top, a roof blew off a barn and six power poles were toppled, Washington County undersheriff Jon Stivers said.
A motorcycle dealership partially collapsed in Pueblo, Colo., where winds gusted to 64 mph.
In Wyoming's Sweetwater County, wind gusts up to 71 mph damaged a marina at Flaming Gorge Reservoir and broke windows at the Western Wyoming Community College in Rock Springs, according to the National Weather Service.
About 1,200 customers in Rock Springs lost power Monday afternoon after winds broke a cross-arm at the top of a power pole. Some residents in Lamont, a small town north of Rawlins, were without power Tuesday. Repair crews used snowcats to access the downed lines, Rocky Mountain Power Company spokesman Jeff Hymas said.
Cold temperatures that made it feel more like January or February engulfed the entire state with many areas expecting daytime temperatures in the teens and 20s. A record low temperature was set at Douglas in central Wyoming when the temperature dropped to 14 degrees early Tuesday. The previous record was 17 set in 2000.
The same storm system toppled trees in San Francisco, produced gusts over 80 mph in southern California and kicked up a dusty haze in Phoenix on Monday, closing a stretch of Interstate 40 in northern Arizona.
Associated Press writers Colleen Slevin and Alexandra Tilsley contributed to this report from Denver.