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Minneapolis/St. Paul, Minnesota Hailstorm and Flash Flood of 1 July 1997

On 1 July 1997, a very intense complex of severe thunderstorms moved across the Minneapolis/St. Paul MN metroplex at approximately 7 PM CDT. The image on the left is the severe storm complex as it appeared on radar at approximately 715 PM. During this event, numerous motorists stopped near and under highway overpass bridges to seek shelter from golf ball-sized hail, up to 100 mph wind gusts, and blinding rainfall. However, the real problem quickly became the extreme rainfall rates of 4 to 6 inches per hour associated with this storm complex, which created a rapidly-developing, and severe urban flash flood situation. The image on the right is a rain gage trace from the University of Minnesota St. Paul campus showing 2.1 inches of rain in 20 minutes! The result? Many motorists were trapped by rising flash flood waters in the very areas around the overpasses where they were seeking shelter from the storm! There were several instances of storm sewer caps being blown off by the intense water pressure and many low-lying areas of interstate highways became fast-flowing rivers from which people had to be rescued.

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