Northeast South Dakota found itself in the grip of catastrophic flooding on the night of May 5th through the 6th, 2007, as a relentless line of thunderstorms swept across the region. The day began as an area of low pressure with abundant moisture from the Gulf of Mexico with powerful low-level winds lifted across South Dakota, unleashing what meteorologists termed as "training thunderstorms."
These training thunderstorms, characterized by repetitive storms crossing the same area, unleashed torrential rains ranging from 3 to over 10 inches across the area.
May 5th rainfall totals from the National Weather Service in Aberdeen included:
5.82 inches in Conde
6 inches in Langford
6.33 inches in Gann Valley
6.72 inches in Clark
7.41 inches in Ashton
7.49 inches in Stratford
7.55 inches near Mellette
7.97 inches in Aberdeen
8.02 inches in Redfield
8.73 inches in Columbia
8.74 inches in Groton
Groton's 8.74 inches of rainfall set a new 24-hour state rainfall record.
Totaling up the rainfall over the two-day event, Aberdeen received a total of 9.00 inches; Columbia received a total of 10.19 inches; Groton received an astonishing two-day total rainfall of 10.74 inches.
Dozens of cities bore the brunt of the flash floods, with hundreds of homes,and businesses succumbing to the deluge. The hardest hit was Aberdeen, where 75% of homes experienced flooding in basements. Structural damage was widespread, with collapsed basement walls and overwhelmed drainage systems leading to sewage backups across the Hub City.
The waters caused thousands of acres of crops to be flooded, and large quantities of fertilizer washed away. Flood warnings were issued for the James River, where downstream, the river would rise quickly to near historic levels
In response to the disaster, President George W. Bush declared several counties, including Brown, Buffalo, Clark, Day, Marshall, and Spink, as disaster areas, unlocking federal aid for relief efforts. South Dakota Governor Mike Rounds also declared a state of emergency for the flooded counties, mobilizing resources to address the crisis.
The night of May 5th, 2007, was not limited to flash floods as the same weather system spawned twenty tornadoes in the southeastern part of South Dakota, including an EF3 that destroyed a hunting lodge near Plankinton.
The floods of May 5-6th, 2007 are an event for which most locals have a story. Just ask them.
