A powerful line of thunderstorms developed ahead of a cold front that moved across eastern Iowa during the late afternoon and evening hours of August 28th. The line of thunderstorms produced damaging winds mainly south of a line from Cedar Rapids to Clinton Iowa. This line of storms also produced a tornado that traveled across Scott and Clinton Counties. There were also swaths of more intense damaging winds in Clinton, Henry, Iowa, and Scott Counties. The heaviest rain fell south of Interstate 80, where 2 to 4 inch amounts were reported.

Thunderstorm Wind in CLINTON, IOWA
From 28-AUG-18 18:37:00 to 28-AUG-18 18:37:00 (CST-6)
Location: ELVIRA
Magnitude: 78.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A NWS Storm Survey Team found extensive damage to corn in the area. In Elvira, the roof of a large farm building was removed by the wind. Trees were also snapped in town.  The wind speeds were estimated to be in the 80 to 90 MPH range.

Thunderstorm Wind in JOHNSON, IOWA
From 28-AUG-18 17:28:00 to 28-AUG-18 17:28:00 (CST-6)
Location: IOWA CITY MUNI ARPT
Magnitude: 72.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in LOUISA, IOWA
From 28-AUG-18 17:24:00 to 28-AUG-18 17:24:00 (CST-6)
Location: COLUMBUS CITY
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in HENRY, IOWA
From 28-AUG-18 19:10:00 to 28-AUG-18 19:10:00 (CST-6)
Location: MT PLEASANT
Magnitude: 74.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Widespread thunderstorm wind damage with down tree limbs, whole trees, and power lines throughout the city of Mount Pleasant.  The peak estimated wind speed was 85 MPH.

Tornado in CLINTON, IOWA
From 28-AUG-18 18:10:00 to 28-AUG-18 18:14:00 (CST-6)
Location: GRAND MOUND
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

An EF-0 tornado touched down near the Scott County and Clinton County line.  Minor damage to tree branches was observed in this area. The tornado strengthened and caused damage to trees and a house. Towards the end of its path, it caused mainly damage to corn. The peak estimated winds were 80 MPH and the tornado was on the ground for 4.14 miles.

Thunderstorm Wind in JOHNSON, IOWA
From 28-AUG-18 17:30:00 to 28-AUG-18 17:30:00 (CST-6)
Location: IOWA CITY MUNI ARPT
Magnitude: 61.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter measured a wind gust of 70 MPH before the power went out. The winds were likely higher.

Thunderstorm Wind in MUSCATINE, IOWA
From 28-AUG-18 17:35:00 to 28-AUG-18 17:35:00 (CST-6)
Location: MUSCATINE MUNI ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorm Wind in SCOTT, IOWA
From 28-AUG-18 17:54:00 to 28-AUG-18 17:54:00 (CST-6)
Location: BUFFALO
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in IOWA, IOWA
From 28-AUG-18 16:28:00 to 28-AUG-18 16:28:00 (CST-6)
Location: MILLERSBURG
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This is the beginning of a swath of thunderstorm wind damage. Numerous trees were damaged in the Williamsburg area.  The peak estimated wind speeds were 75 MPH.

Thunderstorm Wind in JOHNSON, IOWA
From 28-AUG-18 17:15:00 to 28-AUG-18 17:15:00 (CST-6)
Location: NORTH LIBERTY
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported a 24 inch diameter tree was down in their front yard. Time of the event was estimated using radar.

Thunderstorm Wind in JOHNSON, IOWA
From 28-AUG-18 17:30:00 to 28-AUG-18 17:30:00 (CST-6)
Location: IOWA CITY MUNI ARPT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported that a 8 to 12 inch diameter hardwood tree was uprooted.  The spotter noted a measured wind gust of 70 MPH before the power failed. The wind speeds may have been higher.

Thunderstorm Wind in CLINTON, IOWA
From 28-AUG-18 18:04:00 to 28-AUG-18 18:04:00 (CST-6)
Location: WHEATLAND
Magnitude: 70.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A 30 to 40 foot section of roof was blown off the high school. A NWS survey estimated straight line winds of 70 to 80 MPH.

Thunderstorm Wind in HENRY, IOWA
From 28-AUG-18 19:30:00 to 28-AUG-18 19:30:00 (CST-6)
Location: MT PLEASANT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The emergency manager reported power lines down in the city of Mount Pleasant.

Tornado in SCOTT, IOWA
From 28-AUG-18 18:09:00 to 28-AUG-18 18:10:00 (CST-6)
Location: DONAHUE
Tornado F-scale: EF0
Reported by: NWS Storm Survey

An EF-0 tornado touched down near the Scott County and Clinton County line.  Minor damage to tree branches was observed in this area. The tornado strengthened and caused damage to trees and a house. Towards the end of its path, it caused mainly damage to corn. The peak estimated winds were 80 MPH and the tornado was on the ground for 4.14 miles.

Hail in IOWA, IOWA
From 28-AUG-18 16:52:00 to 28-AUG-18 16:52:00 (CST-6)
Location: PARNELL
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in KEOKUK, IOWA
From 28-AUG-18 16:30:00 to 28-AUG-18 16:30:00 (CST-6)
Location: WHAT CHEER
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A public report of large trees down in What Cheer.  The time of the event was estimated using radar.

Thunderstorm Wind in IOWA, IOWA
From 28-AUG-18 16:49:00 to 28-AUG-18 16:49:00 (CST-6)
Location: NORTH ENGLISH
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Broadcast media reported that power lines were down on Highway 149.

Thunderstorm Wind in WASHINGTON, IOWA
From 28-AUG-18 17:10:00 to 28-AUG-18 17:10:00 (CST-6)
Location: WASHINGTON
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported trees down in the city of Washington.

Thunderstorm Wind in IOWA, IOWA
From 28-AUG-18 16:58:00 to 28-AUG-18 16:58:00 (CST-6)
Location: PARNELL
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported numerous trees down all over town. No power at their residence.

Thunderstorm Wind in JOHNSON, IOWA
From 28-AUG-18 17:22:00 to 28-AUG-18 17:22:00 (CST-6)
Location: IOWA CITY
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The Emergency Manager reported power lines and tree branches down in town and south of town.

Thunderstorm Wind in KEOKUK, IOWA
From 28-AUG-18 16:40:00 to 28-AUG-18 16:40:00 (CST-6)
Location: SIGOURNEY
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A public report of trees down in Sigourney. The time of the event was estimated using radar.

Thunderstorm Wind in SCOTT, IOWA
From 28-AUG-18 18:13:00 to 28-AUG-18 18:13:00 (CST-6)
Location: MAYSVILLE
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

This was measured by the Interstate 80 to Interstate 280 Interchange RWIS.

Thunderstorm Wind in CLINTON, IOWA
From 28-AUG-18 18:42:00 to 28-AUG-18 18:42:00 (CST-6)
Location: DEWITT
Magnitude: 51.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Thunderstorm Wind in IOWA, IOWA
From 28-AUG-18 16:49:00 to 28-AUG-18 16:49:00 (CST-6)
Location: PARNELL
Magnitude: 74.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Power poles were snapped and blown down for three quarters of a mile. This is the middle of a path that is about 1 mile wide. There is also widespread tree damage in this area with some trees snapped and crops blown down in this area.

Thunderstorm Wind in CLINTON, IOWA
From 28-AUG-18 18:47:00 to 28-AUG-18 18:47:00 (CST-6)
Location: CLINTON MUNI ARPT
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorm Wind in SCOTT, IOWA
From 28-AUG-18 18:27:00 to 28-AUG-18 18:27:00 (CST-6)
Location: BUFFALO
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported that a tree was down on a house 1 mile east of Hacker Street.

Thunderstorm Wind in IOWA, IOWA
From 28-AUG-18 16:52:00 to 28-AUG-18 16:52:00 (CST-6)
Location: PARNELL
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in SCOTT, IOWA
From 28-AUG-18 17:54:00 to 28-AUG-18 17:54:00 (CST-6)
Location: BUFFALO
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A 10 inch diameter tree down on South Mississippi Street in Bluegrass.

Thunderstorm Wind in IOWA, IOWA
From 28-AUG-18 16:58:00 to 28-AUG-18 16:58:00 (CST-6)
Location: HOLBROOK
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

This is the end of a swath of widespread thunderstorm wind damage with flattened corn.

Thunderstorm Wind in SCOTT, IOWA
From 28-AUG-18 18:10:00 to 28-AUG-18 18:10:00 (CST-6)
Location: SCOTT COUNTY PARK
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A NWS Employee reported a four inch branch down and estimated a wind gust of 60 to 65 MPH.

Thunderstorm Wind in SCOTT, IOWA
From 28-AUG-18 18:12:00 to 28-AUG-18 18:12:00 (CST-6)
Location: BETTENDORF
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A NWS Employee reported numerous 3 to 5 inch diameter branches down between Interstate 74 and Bridge Avenue on Locust Street. The time of the event was estimated using radar.

Thunderstorm Wind in HENRY, IOWA
From 28-AUG-18 19:05:00 to 28-AUG-18 19:05:00 (CST-6)
Location: MT PLEASANT
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported widespread tree damage in the city. Trees were down on cars and homes.  The largest tree was estimated to be about 4 inches in diameter. The time of the event was estimated using radar.

Thunderstorm Wind in LEE, IOWA
From 28-AUG-18 19:45:00 to 28-AUG-18 19:45:00 (CST-6)
Location: KEOKUK
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported multiple trees down in Keokuk. One of them was on down on a road and was around 7 inches in diameter. The time of the event was estimated using radar.

Thunderstorm Wind in LOUISA, IOWA
From 28-AUG-18 17:05:00 to 28-AUG-18 17:05:00 (CST-6)
Location: COLUMBUS CITY
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Thunderstorm Wind in JOHNSON, IOWA
From 28-AUG-18 17:15:00 to 28-AUG-18 17:15:00 (CST-6)
Location: UNIVERSITY HGTS
Magnitude: 71.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The Emergency Manager reported a 71 knot measured wind gust at the Johnson County EMA Building. The time of the event was estimated using radar.