Flash Flood in Marion County, Ohio

Marion county received between 1 and nearly 5 inches of rain on the evening of the 7th. The heaviest rain fell between 930 and 10 PM, where almost 2 inches fell between the City of Marion and La Rue. The USGS rain gage at La Rue measured 4.71 for a storm total, and gages in Marion ranged from 2.5-4.46. The deluge just before 10 PM was the likely trigger for the overwhelmed storm drainage systems resulting in flash flooding in the city. In all 41 individual water rescues were conducted from trapped motorists, and 11 family homes were evacuated and relocated. Several more homes were flooded, primarily in their basements. Only one home and one apartment complex sustained water damage on the first floor. The water table prior to this event was unusually low, and the rivers and creeks were able to handle the runoff across most of the county with minimal damages or impacts apart from closed roads.

A cold front moved slowly southward across Lake Erie and northern Ohio into a moist environment early Labor Day morning. A strong jet aloft fueled persistent moisture advection along with significant backbuilding and training of thunderstorms across the area between about 6am and 6pm Monday. This resulted in a widespread 2-5' of rain with isolated amounts even higher. Later that afternoon, the primary weather hazard shifted to severe thunderstorms with two tornado warnings and three severe thunderstorm warnings being issued, with lots of tree damage and hail up to 2' in diameter, mainly for Knox and Holmes Counties. The night concluded with heavy rain over urban portions of Marion County resulting in significant flooding in the City of Marion.