Flood Watch Issued for Central and Southwest Iowa Tonight as Heavy Rain Threat Increases
The National Weather Service has issued a Flood Watch for portions of central and southwest Iowa from this afternoon through Friday morning as multiple rounds of thunderstorms are expected to bring heavy rainfall to the state.
While some strong to severe storms remain possible, the greatest concern tonight may be flash flooding. Storms are expected to develop and increase in coverage through the afternoon and evening, with some areas potentially seeing several rounds of thunderstorms move over the same location.
Areas Included in the Flood Watch
The Flood Watch includes much of central and southwest Iowa, including:
- Des Moines
- Ames
- Boone
- Perry
- Waukee
- Adel
- Jefferson
- Atlantic
- Winterset
- Indianola
- Creston
- Osceola
- Greenfield
- Corning
- Bedford
- Mount Ayr
- Leon
The watch also includes portions of north-central Iowa, including communities such as Marshalltown, Newton, Pella, Hampton, Iowa Falls, Waterloo, Cedar Falls, and Waverly.
Why Flooding Is Becoming a Concern
A very moisture-rich atmosphere is in place across Iowa, and thunderstorms are expected to become more widespread through the evening and overnight hours.
Forecast data suggests that storms may repeatedly move over the same areas, a process call “training.” When this occurs, heavy rain can accumulate quickly and overwhelm drainage systems, creeks, and streams.
The Weather Prediction Center is highlighting Iowa for a significant heavy rainfall threat this evening, with rainfall rates of 1 to 2 inches per hour possible within the strongest storms.
Rainfall Totals of 2 to 4 Inches Expected
Most locations within the Flood Watch area could receive between 2 and 4 inches of rainfall by Friday morning, with isolated higher amounts possible where thunderstorms repeatedly track over the same area.
Although much of Iowa has experienced relatively dry conditions recently, rainfall may fall faster than the ground can absorb it. This could lead to rapid runoff and localized flash flooding.
Flooding concerns will be highest in:
- Urban areas
- Low-lying roads
- Areas with poor drainage
- Small creeks and streams
- Locations that have received recent rainfall, especially parts of southwest Iowa
Timing
The threat for heavy rainfall and flash flooding will increase late this afternoon and continue through the overnight hours.
The highest risk appears to be between 6 PM and 4 AM, when repeated rounds of thunderstorms are expected to impact portions of central and southwest Iowa.
Stay Weather Aware Tonight
If Flash Flood Warnings are issued, be prepared to act quickly.
Remember:
- Never drive through flooded roadways.
- Turn Around, Don’t Drown.
- Be extra cautious after dark when flooded roads are harder to see.
- Keep your phone charged and weather alerts enabled overnight.
- Have multiple ways to receive warnings while sleeping.
Residents should closely monitor weather conditions through the evening and overnight hours. Have the ISCN Weather app installed and check back with IowaWeather.com for updates as storms develop.