The central portion of the country was primed for an active flood year in 2019 even before it began. Abundant rainfall and early snows moved across the central US towards the end of 2018. Bitter cold temperatures to begin 2019 froze the saturated ground into a solid block of ice. In mid-March, a deep “bomb cyclone,” with the lowest pressure ever recorded for this portion of the United States (969 mb), struck the Central Plains. This cyclone brought unseasonably warm temperatures, abruptly bringing the bitter cold to an end. Some regions of Nebraska had over 10 inches of snow on the ground leading up to the mid-March storm. The cyclone’s precipitation came as rain, and the in situ snowpack melted in less than 24 hours. The combination of rain plus melt on top of frozen ground led to an extreme amount of runoff. Rivers, some of which had 1-to-2 feet thick ice cover, rose rapidly and catastrophically, carrying chunks of ice the size of automobiles downstream; destroying levees, dams, roads: basically everything in its path. In all, over 40 new stage records were set on Midwestern rivers in the wake of the March event. Tragically, eight lives were lost; countless others became homeless and millions of dollars in damage occurred.
This presentation will concentrate on the March “bomb cyclone” event, and how it set the stage for the prolonged high water condition that would characterize the central US for the remainder of 2019.
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