OMAHA, Neb. (AP) -- A late-winter storm system continued its trek across the Midwest, expecting to send rain and snow into Minnesota and Illinois on Friday after leaving devastating flooding in parts of eastern Nebraska and Iowa.
The quickly rising floods evacuated people from their homes, washed out roads in communities, and left farmers worried all the water would drown livestock. The National Weather Service said the system would move into southern Minnesota and parts of Illinois, including Chicago, with rain later turning to snow. But the effects aren't expected to be as bad as what was seen farther west and south on Thursday, said meteorologist Paul Fajman in Omaha.
"With the frozen ground and amount of rain our area had, it was just a perfect set of circumstances that led to the flooding we're seeing in Nebraska and Iowa," Fajman said.
On Wednesday, a blizzard crippled parts of Wyoming, Colorado and western Nebraska.
The heavy rain that fell on top of melting snow in Plains states this week flowed directly into swollen rivers because most of the ground is still frozen. Residents of communities that had to evacuate because of flooding will be cleaning up the damage for some time.
"It was ugly. It still is," Jim Freeman said after using a chainsaw to cut up a chunk of ice that floodwaters left in his driveway. "There's a lot of damage."
Many of the homes in Freeman's neighborhood in Fremont, Nebraska, were inundated by the water that flowed in from the Platte River.
Evacuations also occurred in several other eastern Nebraska communities and in some areas of western Iowa. The weather service said flooding will likely continue on some rivers, including the Missouri River, into this weekend.
Fajman said parts of northeastern Iowa also can expect more flooding Friday and into the weekend. On Thursday, Iowa Gov. Kim Reynolds signed an emergency disaster proclamation and activated the state emergency operations center, and all or part of nine state parks were closed due to rising floodwaters.
Emergency crews responded after a vehicle was swept off a road in Norfolk, Nebraska, and rising water along the Elkhorn River prompted evacuations in the city of 24,000 people. The missing motorist had not been found by late Thursday.
South Dakota Gov. Kristi Noem closed all state offices Thursday as the blizzard conditions moved in, and later in the day ordered the opening of the state's Emergency Operations Center to handle the response to the blizzard and flooding. The state was preparing an emergency declaration, Noem said. The Red Cross opened shelters in Sioux Falls and Yankton.
Rainfall records were set Wednesday in Sioux Falls, South Dakota, and Sioux City, Iowa.
"We've got a lot of water, and it's got to find a way to get out of here," said Tracy West, mayor of Lennox, South Dakota.
The system was moving out of the central Plains on Thursday, but weather service meteorologist Peter Rogers said flooding is likely to persist into the weekend in parts of South Dakota, Minnesota and Iowa, with deeply frozen ground preventing rain and snowmelt from soaking into the soil.
The massive late-winter storm hit Colorado on Wednesday, causing widespread power outages, forcing the cancellation of hundreds of flights and wreaking havoc on roadways. A wind gust clocked in at 97 mph (156 kph) in Colorado Springs.
The culprit was a sudden and severe drop in ground-level air pressure in Colorado, the most pronounced dive since 1950 and something "that will go down in the history books," said Greg Carbin, chief of forecast operations for the National Oceanic and Atmospheric Administration's Weather Prediction Center.
It was caused by a combination of the jet stream and normal conditions in the wind shadow of the Rockies. Air rushed into the low-pressure area and then rose into the atmosphere, causing severe weather.
Meteorologists call the rapid change in pressure a "bomb cyclone" or "bombogenesis."
The window-rattling storm brought blizzards, floods and tornadoes, stretching from the northern Rocky Mountains to Texas and beyond.
In the Texas Panhandle, a utility worker was killed Wednesday while working to restore power amid strong winds pushed in by the storm. And in New Mexico, 36 miners at a nuclear waste repository were trapped underground in an elevator for about three hours because of a power outage caused by the extreme weather.
The storm also contributed to the death of Daniel Groves, a Colorado State Patrol officer who was hit and killed by a car as he helped another driver who had slid off Interstate 76 near Denver.
About 50 National Guard soldiers and airmen used specialized vehicles with tank-like treads to rescue 75 people stranded in their cars during the storm.
Five people were hurt and 150 dairy cows had to be euthanized when a tornado hit the small town of Dexter, New Mexico, on Tuesday. A tornado touched down Thursday in western Kentucky , damaging utility lines and trees. There were no immediate reports of injuries.
In Michigan, a tornado touchdown was reported Thursday in Vernon, southwest of Flint, and in nearby Durand. Michigan State Police said first-responders confirmed at least 21 homes were damaged, but no injuries were immediately reported.