A fast moving complex of severe thunderstorms developed and tracked over much of eastern Iowa, northwest Illinois, and northeast Missouri, as an area of low pressure lifted northeast into northwest Iowa. Widespread damaging winds, large hail, frequent lightning, and a few brief tornadoes were reported.

Thunderstorm Wind in WHITESIDE, ILLINOIS
From 17-MAY-17 17:36:00 to 17-MAY-17 17:36:00 (CST-6)
Location: ROCK FALLS
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

KWQC relayed a report of a tree blown down onto a home on 6th Avenue.

Thunderstorm Wind in HENRY, ILLINOIS
From 17-MAY-17 20:35:00 to 17-MAY-17 20:35:00 (CST-6)
Location: SHADY BEACH
Magnitude: 60.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A NWS storm survey team reported several large trees were blown down along Highway 92 north of of Geneseo.

Hail in HENRY, ILLINOIS
From 17-MAY-17 20:22:00 to 17-MAY-17 20:22:00 (CST-6)
Location: MORRISTOWN
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported hail between the sizes of dimes and quarters.

Hail in HENRY, ILLINOIS
From 17-MAY-17 20:30:00 to 17-MAY-17 20:30:00 (CST-6)
Location: GENESEO
Magnitude: 0.88 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

Thunderstorm Wind in STEPHENSON, ILLINOIS
From 17-MAY-17 18:05:00 to 17-MAY-17 18:05:00 (CST-6)
Location: FREEPORT
Magnitude: 50.00 EG
Crop damage: 0.00K
Reported by: Law Enforcement

The local law enforcement reported a large tree blown down and was blocking the road on the east side of Freeport.

Thunderstorm Wind in HENRY, ILLINOIS
From 17-MAY-17 20:25:00 to 17-MAY-17 20:25:00 (CST-6)
Location: CLEVELAND
Magnitude: 55.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Numerous trees and some farm outbuildings were blown down along route 6 between Colona and Geneseo.

Thunderstorm Wind in HENRY, ILLINOIS
From 17-MAY-17 21:24:00 to 17-MAY-17 21:24:00 (CST-6)
Location: GALVA
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A NWS storm survey observed numerous trees were blown over and limbs broken off in Galva.

Thunderstorm Wind in WHITESIDE, ILLINOIS
From 17-MAY-17 21:40:00 to 17-MAY-17 21:40:00 (CST-6)
Location: PROPHETSTOWN
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

A NWS storm survey team observed tree damage in Prophetstown.

Thunderstorm Wind in HENRY, ILLINOIS
From 17-MAY-17 21:41:00 to 17-MAY-17 21:41:00 (CST-6)
Location: KEWANEE
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Local law enforcement reported power lines were down in town.

Thunderstorm Wind in BUREAU, ILLINOIS
From 17-MAY-17 22:15:00 to 17-MAY-17 22:15:00 (CST-6)
Location: PRINCETON
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The county emergency manager reported power lines and trees down from Princeton to La Moille along route 34.

Thunderstorm Wind in JO DAVIESS, ILLINOIS
From 17-MAY-17 20:33:00 to 17-MAY-17 20:33:00 (CST-6)
Location: WARREN
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated wind gusts of 50 to 60 mph.

Thunderstorm Wind in STEPHENSON, ILLINOIS
From 17-MAY-17 21:25:00 to 17-MAY-17 21:25:00 (CST-6)
Location: FREEPORT
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated wind gusts of 60 mph.

Thunderstorm Wind in STEPHENSON, ILLINOIS
From 17-MAY-17 21:38:00 to 17-MAY-17 21:38:00 (CST-6)
Location: FREEPORT
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter estimated wind gusts up to 60 mph.

Tornado in MERCER, ILLINOIS
From 17-MAY-17 19:00:00 to 17-MAY-17 19:07:00 (CST-6)
Location: GRIFFIN
Tornado F-scale: EF1
Property damage: 25.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Tornado was rated a higher end EF-1 with peak winds 105 mph, a path length of 5.73 miles with a max path width of 150 yards.  This higher end EF-1 tornado caused damage to numerous farm outbuildings, a few homes and trees across Mercer and Henry counties.  One house partially lost a roof while another was impelled by flying debris. Approximately 30 to 40 trees were snapped at the trunks, a couple of dozen were uprooted, with about 50 trees experiencing limb damage.  This tornado continued into Henry county.

Tornado in HENRY, ILLINOIS
From 17-MAY-17 19:44:00 to 17-MAY-17 19:47:00 (CST-6)
Location: HOOPPOLE
Tornado F-scale: EF1
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Tornado was rated EF-1 with peak winds 95 mph, a path length of 2.06 miles and max path width of 50 yards. Damage was mainly to large branches and a few uprooted trees and snapped trunks. Damage was noted to one out building with partial removal of its roof.

Tornado in HENRY, ILLINOIS
From 17-MAY-17 20:20:00 to 17-MAY-17 20:21:00 (CST-6)
Location: GALVA
Tornado F-scale: EF2
Property damage: 40.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Tornado was rated EF-2 with peak winds of 120 mph, a path length of 1.29 miles and a max width 50 yards. Damage was to two snapped power poles, one home with significant damage to shingles. Another house had had roof completely removed and blew out doors with one minor injury at this location.

Tornado in ROCK ISLAND, ILLINOIS
From 17-MAY-17 16:04:00 to 17-MAY-17 16:05:00 (CST-6)
Location: ILLINOIS CITY
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Storm Chaser

Tornado was rated EF-0 with peak winds of 70 mph. a path length of .71 miles and max width 25 yards.  Observed by a storm chaser with video evidence of the circulation detailed a tornado that lasted about a minute, no damage was observed.

Tornado in HENRY, ILLINOIS
From 17-MAY-17 19:07:00 to 17-MAY-17 19:09:00 (CST-6)
Location: MINERAL
Tornado F-scale: EF1
Property damage: 15.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Tornado was rated a higher end EF-1 with peak winds 105 mph, a path length of 2.38 miles with a max path width of 150 yards.  This higher end EF-1 tornado caused damage to numerous farm outbuildings, a few homes and trees across Mercer and Henry counties.  One house partially lost a roof while another was impelled by flying debris. Approximately 30 to 40 trees were snapped at the trunks, a couple of dozen were uprooted, with about 50 trees experiencing limb damage.  This tornado is a continuation of the tornado that touched down in Mercer county.