⚠️ Flash Flood Warning – Boone, IA; Jasper, IA; Marshall, IA; Polk, IA; Story, IA – Monday, July 20, 2026

Flash Flood Warning issued July 20 at 7:35PM CDT until July 21 at 1:45AM CDT by NWS Des Moines IA

Details

FFWDMX

The National Weather Service in Des Moines has issued a

* Flash Flood Warning for…
Southeastern Boone County in central Iowa…
Northwestern Jasper County in central Iowa…
Southwestern Marshall County in central Iowa…
Northern Polk County in central Iowa…
Southern Story County in central Iowa…

* Until 145 AM CDT Tuesday.

* At 735 PM CDT, Doppler radar indicated thunderstorms producing
heavy rain across the warned area. Between 2 and 3 inches of rain
have fallen. Additional rainfall amounts of 1 to 2 inches are
possible in the warned area. Flash flooding is ongoing or expected
to begin shortly.

HAZARD…Flash flooding caused by thunderstorms.

SOURCE…Radar.

IMPACT…Flash flooding of small creeks and streams, urban
areas, highways, streets and underpasses as well as
other poor drainage and low-lying areas.

* Some locations that will experience flash flooding include…
Ames, Ankeny, Nevada, Bondurant, Huxley, Mitchellville, Colfax,
Slater, Iowa State Center, Big Creek Lake, Maxwell, Cambridge,
Elkhart, Collins, Alleman, Sheldahl, Kelley, Mingo, Valeria and
Ames Municipal Airport.

Instructions

For the latest stream observations and forecasts refer to
weather.gov/desmoines/water.

Turn around, don’t drown when encountering flooded roads. Most flood
deaths occur in vehicles.

This alert was automatically posted by SkyGuard, MWSC’s severe weather alerting system. Source: National Weather Service.