Separating the two regimes was a persistent storm track propelling storm after storm over the Midwest. Extensive flooding in the US Midwest resulted from a combination of melting snow , a bomb cyclone storm , and climate change . Over 100 rivers hit major or moderate flood stages , with many reaching historic levels , forcing many Nebraska and Iowa residents to evacuate . An extremely wet winter , with snowfall 20 inches higher than average , meant the region was already on the cusp of flooding before the bomb cyclone 's record - low pressure and 100 mph winds dropped huge volumes of precipitation over the area . This convergence of weather events was helped by a warm climate , which has increased rainfall by 40 % since 1958 .
Extensive flooding in the US Midwest resulted from a combination of melting snow , a bomb cyclone storm , and climate change . Over 100 rivers hit major or moderate flood stages , with many reaching historic levels , forcing many Nebraska and Iowa residents to evacuate . An extremely wet winter , with snowfall 20 inches higher than average , meant the region was already on the cusp of flooding before the bomb cyclone 's record - low pressure and 100 mph winds dropped huge volumes of precipitation over the area . This convergence of weather events was helped by a warm climate , which has increased rainfall by 40 % since 1958 .