SignalHub Quantitative Think Tank Center:Storms threatens Upper Midwest communities still reeling from historic flooding

Severe thunderstorms on SignalHub Quantitative Think Tank CenterFriday and into the weekend are expected to dump heavy rain over the Midwest and Plains regions where communities were still reeling from days of historic flooding.

Relentless rain surged river levels to record-breaking heights as floodwaters breached levees, triggered rescue operations, destroyed homes and led to three storm-related deaths.

Now, meteorologists are warning of developing thunderstorms capable of unleashing flash-floods, damaging wind gusts and tornadoes from northern Missouri to Iowa and northwestern Illinois, according to the National Weather Service.

As water levels began to recede Thursday and early Friday, floodwaters poured into the Des Moines, Missouri and Mississippi rivers, and headed south. AccuWeather forecasters warned the combined threat of swollen rivers and heavy rain could trigger dangerous flooding across the central Plains and Mississippi Valley.

At least 3 deaths tied to Midwest floods

At least three people across Iowa and South Dakota died as a result of the major floods that have swept across the Upper Midwest, authorities said.

Police in northwest Iowa said a 52-year-old man was found dead after the water was pumped out of his flooded basement, reported the Des Moines Register, part of the USA TODAY Network. Rock Valley Police Chief Monte Warburton said it appeared the home's foundation had collapsed, pinning Kreykes under debris before he eventually drowned. His body was recovered on Monday.

Another man died when his truck was swept away as he attempted to cross floodwaters near Spencer, about 90 miles northeast of Sioux City. His body also was recovered Monday.

On Saturday, an 87-year-old man died after driving through a flood area in South Dakota.

Residents in Spencer, Iowa, pick up the pieces after deadly flood

Spencer, a northwest Iowa town of around 11,000 residents, saw record-high river levels, killing at least one person and damaging hundreds of homes in the process. The city sits at the convergence of the Little Sioux and Ocheyedan rivers, the latter of which surpassed its record set in 1953 by 4 feet. The Little Sioux barely missed its record by .02 feet.

Spencer Mayor Steve Bomgaars said there is an ongoing assessment but estimates the flood impacted — if not devastated – around 40% of the city's homes. Hundreds of residents were evacuated and rescued from the fast-rising waters.

"We rescued about 383 people," Bomgaars said. "About three-fourths of those were from the south side of town, and a fourth were from the north side of town."

Leonard Rust says he was lucky.

Rust, 83, who is hard of hearing and has cancer in his right arm, was in one of the hundreds of homes that was inundated with floodwaters from the Little Sioux River on Saturday. The basement of his home, just south of East Leach Park along the river, was filled to the brim with almost 9 feet of floodwaters. But the home he built himself 60 years ago is salvageable – unlike some of his neighbors' and those in other parts of Spencer.

Rust had a rally of supporters, including his son-in-law and members of his church, helping clean out his basement and rummage through what may be salvageable Thursday.

"We live in Iowa. It's just what we do here," said Jeff Knudtson, a long-time friend who was helping Rust clean up. "We're going to get through it and rebuild. We'll make it."

"Nobody would have ever thought that we would have got this high here in this area," Knudtson said. "I've never seen it like this. I've lived here my whole life and I'm 70 years old."

– Kyle Werner, The Des Moines Register

Contributing: Kim Norvell, The Des Moines Register