More than 10 million people in the Midwest and Great Plains remain under flood warnings following what the National Weather Service called "major and historical river flooding" along parts of the Missouri and Mississippi river basins that left at least three people dead.

Areas in the Midwest currently ravaged by floodwaters are expected to see some relief in the coming days as water begins to recede and head downstream. However, that could bring rising waters for locations down the Mississippi River all the way to the Gulf of Mexico.

Forecasters said the flooding won't be as severe at downstream locations but warned that those areas should still expect to see moderate to major flooding.

Heavy rain and melting snow that overpowered the Missouri River forced hundreds of families out of their homes over the weekend and forced the base that is home to U.S. Strategic Command to sharply scale back operations on Sunday.

Nebraska has been particularly hard hit by historic floods in the wake of an intense winter storm. On March 16, 2019, the Operational Land Imager (OLI) on Landsat 8 captured a false-color image that underscores the extent of the flooding on the Platte, Missouri, and Elkhorn Rivers. For comparison, the first image is from March 20, 2018 and the second image shows the same area on March 16, 2019. Joshua Stevens / NASA Earth Observatory

At least three people are confirmed to have died. State emergency management officials in Nebraska said a 50-year-old farmer was swept away while helping someone else escape from a vehicle in floodwaters on Thursday. They said an elderly resident also died in rising waters after having refused to leave home; no further details were immediately available.

In Iowa, Aleido Rojas Galan, 55, died after he was submerged in floodwaters on Friday in the town of Riverton, the Fremont County Sheriff's Office said.

Nearly 40 counties in Iowa have declared an emergency, a spokesman for the Iowa Emergency Management told NBC News Monday. In Nebraska, more than 50 counties declared a state of emergency.

Officials in Wisconsin said Monday that conditions in the state are improving and building inspectors are in the process of letting residents know if they can return home.

Several communities west of Omaha (between the Elkhorn and Platte Rivers) either flooded or temporarily became islands as floodwaters encroached from both sides. One third of Offutt Air Force Base was inundated and 30 buildings were damaged, according to news reports. Rising flood waters forced people in dozens of communities to evacuate. Joshua Stevens / NASA Earth Observatory

A storm system is expected to bring light rain this week to those areas already experiencing flooding, but will not be as severe as the storm that slammed the Midwest last week, according to forecasters. This new storm is said to bring a small amount of rain.

In Atchison County, officials urged more than a hundred people to leave their homes as water levels rose and strained levees, three of which had already been overtopped by water. Missouri State Highway Patrol crews were on standby to rescue anyone who insisted on staying.

“The next four to five days are going to be pretty rough,” said Rhonda Wiley, Atchison County’s emergency management and 911 director.

The Missouri River reached 30.2 feet in Fremont County in far southwestern Iowa on Sunday, breaking the record by 2 feet and topping levees in the towns of Bartlett and Thurman. A levee was breached on the Platte River near North Bend, northwest of Omaha, Nebraska, on Sunday afternoon; authorities urged all residents to move to higher ground immediately.

Nebraska Emergency Management Agency said Sunday it was monitoring 17 flood locations across the state and expected more record crests in the next 24 to 48 hours.

Also on Sunday, Iowa Gov. Kim Reynolds said 38 counties have received a disaster proclamation and more than 110 homes were damaged by floods in the western city of Hornick. She and the governors of Nebraska and Wisconsin all declared states of emergency.

U.S. Strategic Command, or StratCom, which oversees the U.S. strategic nuclear forces from Offutt Air Force Base near Omaha, said Sunday that floodwaters had overwhelmed the southeastern side of the base despite the deployment of more than 235,000 sandbags and 460 flood barriers.

Base commanders told NBC affiliate WOWT of Omaha that the flooding was affecting as much as two-thirds of the more than 16,000 active-duty and civilian personnel at the base — which, in addition to hosting StratCom, is home to the 55th Wing, the largest wing within Air Combat Command.

"We wanted to stay ready, and fortunately we were able to save all of our critical capability, and we are still in the fight," said Col. Michael Manion, commander of the 55th Wing.