May 2007 Tornado Outbreak - Non-tornadic Events

Non-tornadic Events

In addition to the tornadoes, widespread flooding occurred across central North America as a result of the same system producing continuous thunderstorms. There were two major reasons for the flooding: The storm system itself moved very slowly, having produced significant tornado outbreaks in almost the same places for three days. In addition, the storms moved along each other's paths, so one storm dropped heavy rains on the same place that the storm before it did (this is also known as "training").

Across portions of eastern Nebraska and western Iowa, rainfall amounts exceeded locally 6 inches (152 mm). In northeastern and central Kansas, rainfall amounts approached 5 – 6 inches locally (125 – 150 mm). In North Dakota, southern Manitoba and southern Saskatchewan, heavy rainfalls of 1 – 3 inches (25 – 75 mm) fell from this system from May 4 to May 7. Similar amounts were reported in Alberta on May 3 and May 4.

Some of the worst flooding affected Topeka, Kansas, where several rescues had to be made, and the Kansas City Metro Area, where several roads were closed. In neighboring Missouri, levees broke along the Missouri River which caused extensive flooding to hundreds of homes and the northwest and central part of the state. The National Guard were assisting on filling sandbags to protect homes, schools and plants across the state which experienced some of the worst flooding since the Great Flood of 1993 which affected most of the Mississippi River Valley. Torrential rains on May 10 had also caused flooding in parts of southern Missouri as well as in eastern Kansas. The heavy rains also affected activities surrounding the Riverfest (Wichita River Festival) which postponed some events until May 14. The Arkansas River reached record levels near Haven when it crested at 13.08 feet on May 8. Some flooding into low lying areas was also observed in the Wichita Metropolitan Area. Rainfall amounts in southern and southeastern Kansas also exceeded 6 inches (152 mm) over a two-day period on May 6 and May 7. There were several reports of farmers who lost several cattle who have been toss by the high water levels.

In Aberdeen, South Dakota, 7.75 inches (197 mm) of rain fell the evening of May 5 into the early morning hours of May 6, causing significant flooding in some areas around the city. It was also the city's new 24–hour record rainfall, breaking the old mark of 5.20 inches (132 mm) set in June 1978. The highest unofficial rainfall total was reported in Epiphany, South Dakota where as much as 10 inches (254 mm) fell during the weekend. The highest official report of rain, 8.73 inches (222 mm) at Columbia, South Dakota, set a new official 24–hour May rainfall record for the entire state of South Dakota.

In southern Oklahoma City and surrounding communities, strong straightline winds caused damage to several buildings and downed trees and power lines in the early morning hours of May 7, with cleanup efforts being complicated due to flooding rains accompanying the storm. About 11,000 homes were without power during the event. There were also reports of floods across many other areas in Oklahoma. Oklahoma Governor Brad Henry had declared a state of emergency for all 77 counties across the state due to all the severe weather including the tornadoes, the flash floods and hail.

Snow was also reported across higher elevations in Colorado, Wyoming, Nebraska and Utah with local amounts of up to one foot (30 cm) across central Colorado.