Flash Flood — Dubuque, Iowa

1999-05-16 to 1999-05-17 · near Dyersville, Dubuque, Iowa

Event narrative

Flash flooding along the The North Fork of the Maquoketa River caused extensive damage in Dyersville. Numerous businesses across town sustained major damage. The costliest damage occurred at Scale Models, which sustained an estimated $150,000 in damage. Other businesses reported flooding to depths of 7 feet in their basements. About 100 people were evacuated from 60 homes. State officials set the preliminary damage estimates from Dyersville at $3 to $5 million.

Wider weather episode

Summary of events of May 16-17, 1999:Two lines of thunderstorms developed over Iowa: one north to south across western Iowa and moved east, and the other repeatedly developed east to west from Butler to Clayton counties in northeast Iowa and moved east. The training of thunderstorms in the northern line dropped extremely heavy rains across portions of northeast Iowa, with an unoffial rainfall total of 8 inches just north of Buchanan County. The storms produced severe weather of nearly every type, including large hail (up to the size of golf balls in Fairbank in Buchanan County), damaging winds, funnel clouds, and flash flooding. Although there were no confirmed tornadoes, it is believed that some of the thunderstorm wind damage was enhanced in some places by gustnado development along the leading edge of the squall line. The most extensive wind damage (with at least 2 minor injuries) occurred in Cedar Rapids and Walker in Linn County. Other hard-hit areas included Sigourney (Keokuk County), Washington and West Chester (Washington County), Baldwin and Miles in Jackson County, and rural Jones County near Onslow and Wyoming. Other reports of wind damage to trees and power lines came from Benton, Jones, Muscatine, and Johnson Counties. The winds also derailed a train near Lowden in Cedar County. After the widespread heavy rain, flash flooding soon developed, with the most extensive flash flooding from Buchanan county eastward across Delaware and Dubuque Counties into Jo Daviess County in Illinois. The North Fork of the Maquoketa River surged quickly out of its banks, flooding portions of Dyersville (Dubuque County). Much of Dubuque County also suffered major damage from flash flooding. (See also Storm data entries for northwest Illinois for details on the damage in East Dubuque in Jo Daviess County Illinois.)By mid-morning on the 17th, the flash flooding had turned into extensive river flooding and then eventually became a record flood on the Wapsipinicon River. See the following Flood entry for details.

Source: NOAA Storm Events Database, event_id 5715125. Narrative written by the NWS forecast office that issued the report.