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Tornado in Winnebago County, Iowa

Tornado August 17, 2025 · Winnebago County, Iowa

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Not rated
0.4 mi
Path length
35 yd
Path width
EF0EF1EF2EF3EF4EF5Unrated

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.

Not rated. NOAA lists no rating for this tornado. Ratings come from surveying damage, and the National Weather Service now records “EFU” (unknown) when a tornado hit nothing a survey team could rate.

What the National Weather Service wrote

Satellite imagery revealed a track in agricultural fields, just missing a farmstead. No DIs were impacted, resulting in an EF-U rating.

The wider storm

A warm front was draped across northern Iowa the afternoon and evening of August 17th. Convection developed along the boundary late in the afternoon in a deeply unstable environment with over 4000 J/kg of MLCAPE. Shear was lacking an prevented storm organization and more robust development, with around 25 kts of effective shear. Low level CAPE was high at over 200 J/kg in the 0-3 km and allowed for stretching of the updraft, resulting in a brief tornado in northern Iowa. This tornado remained over cropland and did not result in tree or structural damage, hence the EF-unknown rating.

Began near Neils (43.2651, -93.7775).

Source: NOAA Storm Events Database, event 1297496. Narratives are written by the National Weather Service forecast office that issued the report.

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