Flood waters continue to rise across the United States and there are fears that many parts of the Mississippi River will remain above flood stage for a further two or three months.

Many waterways across the Great Plains into the Midwest have been hit by heavy spring rains. That accompanied by rapid snowmelt and ice jams have led to a massive and destructive rise in water levels.

The Mayor of Atchison, Kansas, Shawn Rizza, monitored the increased water level of the Missouri River from a Kansas Highway Patrol aircraft on Friday.

Rizza encouraged residents of Atchison to volunteer for cleanup activities as the water recedes.

The flood crest was expected to reach the Kansas towns of Atchison and Leavenworth, about 55 kilometres further downstream, on Saturday, and Kansas City as early as Sunday, officials said.

Missouri River flooding was triggered by last week’s ”bomb cyclone” storm, which killed at least four people in Nebraska and Iowa, left a man missing below Nebraska’s collapsed Spencer Dam, and inflicted an estimated $1.5bn in damages in Nebraska.

On Thursday, the National Oceanic and Atmospheric Administration (NOAA) issued their spring outlook. They report that the situation for the central US is soon going to get much, much worse.

“The extensive flooding we’ve seen in the past two weeks will continue through May and become more dire and may be exacerbated in the coming weeks as the water flows downstream,” said Ed Clark, director of NOAA’s National Water Center in Tuscaloosa, Alabama, in a statement.

“This is shaping up to be a potentially unprecedented flood season, with more than 200 million people at risk for flooding in their communities.”

Of the total, about 41 million people are at risk for moderate flooding and 14 million more for major flooding.