Flash Flood — Dubuque, Iowa

2011-07-27 to 2011-07-28 · near White Pine Hollow Sp, Dubuque, Iowa

Event narrative

Torrential downpours of rain fell across much of Dubuque County during the evening of July 27 and early morning hours of July 28 resulting in flash flooding of much of the county, especially in Dubuque, IA. Rainfall totals of 7 to 15 inches were common across the area, with most of the rain falling in under 12 hours.

Numerous roads and bridges were washed out and many others closed, causing Dubuque County to run out of barricades. Several neighborhoods were evacuated, including the Valley Hill trailer park where the water was 6 feet deep. Many creeks in the area raged out of their banks, including Catfish Creek. Very early estimates of damage to infrastructure alone exceeded $3 Million. Numerous roads and streets were flooded, with some eroded or washed away completely. Among the hardest hit areas was the vicinities of St. Mary's Catholic Church, Elm Street and the Millwork District. The Dubuque water treatment plant was heavily damaged, with estimates between $1.5 Million and $2 Million. A basement wall caved in at 1790 Chaney Road on Dubuque's West End.

Wider weather episode

Hot and humid conditions prevailed across the region July 27, as a warm front lifted northward into northeast Iowa. Showers and thunderstorms developed along the Highway 20 corridor in Dubuque, Jo Daviess and Stephenson Counties during the early evening hours of July 27. They continued to redevelop and move over the same areas for about 18 hours. Record-setting rainfall totals of 7 to 15 inches resulted in flash flooding of much of the area. The Mississippi River at Dubuque, IA even rose about 4 feet in 12 hours due to the excessive rainfall. In addition to the heavy rains and flooding, some of the stronger storms produced large hail and 2 brief tornadoes. High temperatures on July 27 topped out in the lower and middle 90s. Due to the high humidity levels, low temperatures the morning of July 28 only managed to slip into the 70s and lower 80s.

View location on OpenStreetMap → (42.6178, -91.0959)

Source: NOAA Storm Events Database, event_id 336544. Narrative written by the NWS forecast office that issued the report.