Tornado in Grundy County, Iowa
Tornado August 18, 2025 · Grundy County, Iowa
The path drawn at its surveyed width of 35 yards (0.02 mi) — zoom in and the swath grows to true scale. Other tornadoes recorded nearby that day are shown faint.
What the National Weather Service wrote
Satellite imagery revealed a track in agricultural fields. No DIs were impacted, resulting in an EF-U rating.
The wider storm
A weak shortwave moved across Iowa overnight and through the morning of August 18th. And line of storms with trailing stratiform area passed across the state with the wave through the morning. MLCAPE was around 1500-2000 J/kg with a weak 850 mb low level jet sustaining storms. With weak effective shear around 20 kts or less, storms struggled to organize and did not become severe. As storms moved east, there was a pocket of enhanced low level stability with around 100 J/km of 0-3 km CAPE. This was enough to incur low level stretching and result in a few tornadoes in Grundy County. Tornadoes remained in open cropland and did not result in any structural or tree damage, identified by drone and satellite imagery.
Began near Fern (42.4895, -92.8552).
Other tornadoes from the same storm system
2 more tornadoes the National Weather Service filed under this storm episode.
Source: NOAA Storm Events Database, event 1297861. Narratives are written by the National Weather Service forecast office that issued the report.
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