Flash Flood — Polk, Iowa

2025-07-20 · near Ashawa, Polk, Iowa

Event narrative

Local law enforcement reported flash flooding over portions of the Des Moines metro area on the evening of July 20th 2025. Several intersections closed along 63rd Ave, with several stranded vehicles. George Flagg Parkways closed, with flooding reported in the Valley Junction area. Local media also reported deep, standing water along Ashworth road in West Des Moines.

Wider weather episode

Diurnally driven afternoon storms on Sunday, July 20th, 2025, developed within an unstable environment with CAPE values over 3000 J/kg and 40 to 45 kts of effective shear. Despite this unstable and decently sheared environment, several factors limited the severe weather potential, including weak low-level flow, a warm layer aloft, and an overall lack of forcing. This led to disorganized storms that remained below severe limits. The weak flow and low-level instability did allow for the production of a few funnel clouds in western Iowa, but these remained aloft and posed no threat to lives or property.

The primary impact from these slow-moving storms was heavy rainfall over already saturated ground from the morning's events. One storm developed directly over the Des Moines metro area and slowly drifted southward, dropping an additional 1 to 2 inches of rain on top of the 3 to 4 inches that had fallen early in the day. Drainage systems were quickly overwhelmed, producing street and building flooding in Des Moines and West Des Moines, particularly in areas near the Raccoon River. Fortunately, this flash flooding was short-lived and waters receded by the late evening.

View location on OpenStreetMap → (41.5854, -93.7706)

Source: NOAA Storm Events Database, event_id 1290943. Narrative written by the NWS forecast office that issued the report.