EF1 Tornado — Delaware, Iowa

2023-03-31 · near Oneida, Delaware, Iowa

Event narrative

This EF1 tornado developed southwest of Oneida, IA in Delaware County and moved northeast into Clayton County, IA, around 16:45 LST. This tornado damaged farm outbuildings and trees along its path, determined through ground surveys and Sentinel satellite data, with estimated peak winds around 110 mph. Scour marks on farms were also noted from Sentinel Satellite, as it crossed into Clayton County, about 3 miles west of Colesburg (see NWS LaCrosse StormData for details of tornado in Clayton County).

Wider weather episode

A very strong system developed on the morning of March 31st and tracked across the state of Iowa. This system pulled unseasonably warm and moist air into the Midwest, which combined with a very favorable wind profile to create a volatile environment for severe thunderstorms. Discrete supercell thunderstorms occurred initially, but quickly transitioned into a QLCS mode. This system produced a historic tornado outbreak for the area, with a record 29 tornadoes on the day, including 13 rated EF-2, 1 rated EF-3, and 1 rated EF-4. This was the first EF-4 tornado in the NWS Quad Cities service area since 1995. 11 injuries were reported, with no known fatalities. In addition to the numerous tornadoes, there were many large hail and damaging wind reports. Maximum straight line thunderstorm winds were estimated at 80 to 90 mph.

View location on OpenStreetMap → (42.5250, -91.3720)

Source: NOAA Storm Events Database, event_id 1087063. Narrative written by the NWS forecast office that issued the report.