MPR’s Mark Heistad interviews meteorologist Bruce Watson about what created the conditions for the massive amount of rain that fell on the Twin Cities on July 23, 1987. Watson describes the intensity of rain in six-hour period as something that happens about every 5-10,000 years.

Considered the Twin Cities “Superstorm,” the July 23-24, 1987 event dropped 9.15 inches at the Minneapolis–Saint Paul International Airport, and over 10 inches in suburbs west and southwest of Minneapolis. This rainfall cataclysm produced the worst flash-flooding on record in the Twin Cities. A tornado touched down in Maple Grove.