Flash Flooding in Michigan, August 6, 1998

A warm front, oriented west to east, was located just south of Michigan during the early morning hours. A series of showers and thunderstorms developed just north of the front. These storms moved east, parallel to the warm front, in a typical train-echo pattern. The result was a classic heavy rain event for southeast Michigan. Some rainfall totals were: 5.7 inches in Hudson, 5.09 inches in Manchester, 4.12 inches in Ann Arbor, 3.78 inches in Farmington Hills, and 3.55 inches in Ypsilanti.Southeast Michigan had been quite dry for the past month, and so the soil was able to absorb much of the heavy rain. As a result, flooding problems in rural areas were surprisingly minor, and largely confined to Lenawee County. A few vehicles left in flood prone locations overnight were swamped by high water in the morning.Urban areas were an entirely different story. The increased area covered by impermeable surfaces, such as concrete and buildings, led to rapid runoff despite dry soil conditions. As a result, urban areas in the heavy rain swath saw substantial flooding, including Adrian and Ann Arbor. In Ann Arbor, Mallets Creek rose out of its banks. The creek destroyed sidewalks in the Briarwood Mall area, and swept three cars into a retention pond. Some flooding also took place on the Athletic (South) Campus of the University of Michigan.Although rainfall totals were not as high, flooding also developed further east in the near northwest suburbs of Detroit. Flooded roads played havoc with the morning commute in Southfield, Troy, Livonia, Novi, and other cities. Parts of I-75, I-696, and Woodward Avenue (M-1), were closed. Basements were flooded in Farmington and Royal Oak, and several businesses in Farmington Hills experienced water damage. In Northville, a train derailed when it attempted to cross tracks that were washed out. Nineteen hundred gallons of diesel fuel was spilled as a result.Runoff from the heavy rain resulted in some river flooding, mainly in the more urbanized basins (see below).