Severe thunderstorms moved across northeast Iowa during the evening of May 15th. These storms produced a small, short-lived tornado between Fort Atkinson and Calmar (Winneshiek County). Wind gusts in excess of 60 mph and reports of wind damage were common from Osage (Mitchell County) and Marble Rock (Floyd County) east to Monona and Guttenberg (Clayton County). Large hail was also common with Fort Atkinson getting hit especially hard. The large hail shredded the siding and damaged the roofs on an estimated 70 to 80 percent of the buildings in the town.

Hail in FLOYD, IOWA
From 15-MAY-17 17:21:00 to 15-MAY-17 17:21:00 (CST-6)
Location: WALLER
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in CHICKASAW, IOWA
From 15-MAY-17 17:28:00 to 15-MAY-17 17:28:00 (CST-6)
Location: IONIA
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Quarter sized hail fell near Ionia.

Thunderstorm Wind in CHICKASAW, IOWA
From 15-MAY-17 17:21:00 to 15-MAY-17 17:21:00 (CST-6)
Location: NASHUA
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Trees were blown down south of Nashua.

Hail in CHICKASAW, IOWA
From 15-MAY-17 17:38:00 to 15-MAY-17 17:38:00 (CST-6)
Location: NEW HAMPTON
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Egg sized hail fell south of New Hampton at exit 201 along U.S. Highway 63.

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 17:51:00 to 15-MAY-17 17:51:00 (CST-6)
Location: SPILLVILLE
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Lots of trees were damaged in Spillville.

Hail in CHICKASAW, IOWA
From 15-MAY-17 17:40:00 to 15-MAY-17 17:40:00 (CST-6)
Location: LITTLE TURKEY
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Egg sized hail fell northeast of Little Turkey.

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 17:56:00 to 15-MAY-17 17:56:00 (CST-6)
Location: CALMAR
Magnitude: 71.00 MG
Property damage: 8.00K
Crop damage: 0.00K
Reported by: Amateur Radio

A wind gust to 82 mph occurred in Calmar. Several trees were blown down and one building suffered damage to the siding.

Hail in WINNESHIEK, IOWA
From 15-MAY-17 17:59:00 to 15-MAY-17 17:59:00 (CST-6)
Location: CALMAR
Magnitude: 2.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Egg sized hail fell in Calmar.

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 18:10:00 to 15-MAY-17 18:10:00 (CST-6)
Location: FRANKVILLE
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Numerous trees were blown down south of Frankville.

Thunderstorm Wind in CLAYTON, IOWA
From 15-MAY-17 18:22:00 to 15-MAY-17 18:22:00 (CST-6)
Location: LUANA
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Road signs were blown down east of Postville.

Thunderstorm Wind in CLAYTON, IOWA
From 15-MAY-17 18:19:00 to 15-MAY-17 18:19:00 (CST-6)
Location: MONONA
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

An estimated 65 mph wind gust occurred in Monona.

Thunderstorm Wind in CLAYTON, IOWA
From 15-MAY-17 18:42:00 to 15-MAY-17 18:42:00 (CST-6)
Location: GUTTENBURG
Magnitude: 55.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Roofs were blown off a few buildings in Guttenberg and power lines were down.

Hail in FLOYD, IOWA
From 15-MAY-17 16:57:00 to 15-MAY-17 16:57:00 (CST-6)
Location: MARBLE ROCK
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Quarter sized hail fell in Marble Rock.

Hail in FLOYD, IOWA
From 15-MAY-17 17:20:00 to 15-MAY-17 17:20:00 (CST-6)
Location: CARRVILLE
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 17:48:00 to 15-MAY-17 17:48:00 (CST-6)
Location: FESTINA
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Newspaper

A 30 foot section of a roof was blown off a cattle shed with another shed extensively damaged southeast of Ft. Atkinson.

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 18:09:00 to 15-MAY-17 18:09:00 (CST-6)
Location: OSSIAN
Magnitude: 50.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Newspaper

Significant wind damage occurred to a barn and shed southeast of Ossian.

Hail in MITCHELL, IOWA
From 15-MAY-17 14:59:00 to 15-MAY-17 14:59:00 (CST-6)
Location: ST ANSGAR
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Thunderstorm Wind in MITCHELL, IOWA
From 15-MAY-17 16:45:00 to 15-MAY-17 16:45:00 (CST-6)
Location: OSAGE
Magnitude: 43.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Some trees and power lines were blown down in Osage.

Hail in FLOYD, IOWA
From 15-MAY-17 16:59:00 to 15-MAY-17 16:59:00 (CST-6)
Location: ROCKFORD
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Hail in WINNESHIEK, IOWA
From 15-MAY-17 17:07:00 to 15-MAY-17 17:07:00 (CST-6)
Location: RIDGEWAY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Quarter sized hail fell in Ridgeway.

Thunderstorm Wind in FLOYD, IOWA
From 15-MAY-17 17:11:00 to 15-MAY-17 17:11:00 (CST-6)
Location: CARRVILLE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

An estimated 60 mph wind gust occurred south of Charles City.

Hail in FLOYD, IOWA
From 15-MAY-17 17:11:00 to 15-MAY-17 17:11:00 (CST-6)
Location: CARRVILLE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Quarter sized hail fell south of Charles City.

Thunderstorm Wind in CHICKASAW, IOWA
From 15-MAY-17 17:22:00 to 15-MAY-17 17:22:00 (CST-6)
Location: NASHUA
Magnitude: 56.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Public

Trees were blown down, snapped or uprooted in Nashua from an estimated 65 mph wind gust.

Thunderstorm Wind in CLAYTON, IOWA
From 15-MAY-17 18:24:00 to 15-MAY-17 18:24:00 (CST-6)
Location: GARBER
Magnitude: 55.00 EG
Property damage: 175.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Three barns and a machine shed were destroyed northeast of Garber. Several trees were also uprooted, a garage collapsed and some roof panels were taken off a farm building.

Hail in WINNESHIEK, IOWA
From 15-MAY-17 17:51:00 to 15-MAY-17 17:52:00 (CST-6)
Location: SPILLVILLE
Magnitude: 1.50 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Quarter to walnut sized hail fell in Spillville.

Thunderstorm Wind in FLOYD, IOWA
From 15-MAY-17 16:55:00 to 15-MAY-17 16:55:00 (CST-6)
Location: MARBLE ROCK
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

An estimated 60 mph wind gust occurred in Marble Rock.

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 18:08:00 to 15-MAY-17 18:08:00 (CST-6)
Location: OSSIAN
Magnitude: 57.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Trees were blown down in Ossian blocking U.S. Highway 52.

Tornado in WINNESHIEK, IOWA
From 15-MAY-17 17:45:00 to 15-MAY-17 17:47:00 (CST-6)
Location: CALMAR
Tornado F-scale: EF0
Property damage: 4.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A short-lived EF0 tornado occurred west of Calmar. The tornado started west of 265th Ave between 160th and 175th Streets and traveled southeast across Lake Meyer. A NWS Storm Survey Team found a broken line of tree damage along the path of the tornado.

Hail in CLAYTON, IOWA
From 15-MAY-17 18:22:00 to 15-MAY-17 18:22:00 (CST-6)
Location: MONONA
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Half dollar sized hail fell in Monona.

Hail in WINNESHIEK, IOWA
From 15-MAY-17 17:47:00 to 15-MAY-17 17:47:00 (CST-6)
Location: FT ATKINSON
Magnitude: 2.00 
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Large, wind driven hail pounded Ft. Atkinson. An estimated 70 to 80 percent of the buildings in the town sustained siding and roof damage.

Thunderstorm Wind in FAYETTE, IOWA
From 15-MAY-17 17:58:00 to 15-MAY-17 17:58:00 (CST-6)
Location: FAYETTE
Magnitude: 50.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Trees were blown down and roofs were blown off buildings in the central part of Fayette County.

Thunderstorm Wind in CLAYTON, IOWA
From 15-MAY-17 18:16:00 to 15-MAY-17 18:16:00 (CST-6)
Location: LUANA
Magnitude: 50.00 EG
Property damage: 30.00K
Crop damage: 0.00K
Reported by: Newspaper

Near Luana, the winds lifted up a barn and dropped it several feet away. Some cattle were trapped inside the destroyed barn.

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 17:53:00 to 15-MAY-17 17:53:00 (CST-6)
Location: OSSIAN
Magnitude: 60.00 EG
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Public

Southeast of Calmar, a commodity shed was destroyed with several other buildings damaged, a 30 foot travel trailer was tossed across the yard of a residence and a large pine tree was topped with the debris found a quarter of a mile away.

Thunderstorm Wind in WINNESHIEK, IOWA
From 15-MAY-17 18:08:00 to 15-MAY-17 18:08:00 (CST-6)
Location: CASTALIA
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Newspaper

Several large trees were blown down south of Ossian.