Thunderstorm Wind — Kossuth, Iowa

2025-06-11 · near Algona, Kossuth, Iowa

Event narrative

Social media picture of medium to large tree branch sent through house roof. Time estimated from radar.

Wider weather episode

A surface boundary oriented roughly west southwest to east northeast over northern Iowa provided a genesis region for thunderstorms on June 11 2025. Storms developing along this boundary moved into a very unstable environment south and east of the boundary, boasting MLCAPE values of 2500 to 3000 J/kg. Most of the better wind shear was located along and north of this boundary, but effective shear values of 30 to 40 kts along and just south of this boundary were sufficient for organized storms. Surface temperatures were also quite warm in the warm sector, with afternoon temperatures in the 90s but dewpoints only in the upper 50s to low 60s, resulting in inverted-V soundings and an environment conducive for strong cool production and downburst winds. Thunderstorms were initially discrete, producing strong downburst winds and hail. One storm in far northern Iowa, nearest to the boundary and within a more sheared environment, exhibited supercellular characteristics and produced a very strong rear-flank downdraft (RFD). Wind gusts of over 70 mph were observed with this RFD, some of which extended multiple miles south of the main storm. Personal weather stations showed a nearly 30 degree Fahrenheit temperature drop and 5 to 10 millibar pressure increase accompanying these winds as the RFD/cold pool passed through. The strong winds resulted in tree and building damage beginning near Emmetsburg through Algona and into Belmond. Another storm near Dows produced a healthy core which promptly collapsed, producing a microburst which damaged a machine shed on a farm outside Dows. Upon reaching north central Iowa, storms began to grow upscale as cold pools congealed, transitioning into a linear mode. While this transition occurred, the gust front began to outrun the storms, but continued to produce strong 50 to 60 mph winds as it trudged eastward. A plume of dust accompanied this gust front upon it's arrival in northeastern Iowa. Eventually, storms reoriented themselves along the leading edge of the cold pool, producing more tree damage and power outages throughout the Cedar Falls/Waterloo area. Strong winds continued into Tama county and eastern Black Hawk county, where a semi truck and trailer was overturned on Highway 20. Storms eventually departed the DMX forecast area in the early evening, but continued producing strong winds as they moved through eastern Iowa.

View location on OpenStreetMap → (43.0800, -94.2200)

Source: NOAA Storm Events Database, event_id 1269908. Narrative written by the NWS forecast office that issued the report.