Tornadoes made an October appearance along with other strong storms and heavy rainfall as a number of conditions came together. A frontal boundary stalled out across Iowa, situated from southwest to northeast, roughly cutting the state in half. Dew points were on the high side given the time of the year, in the upper 60s to low 70s, yielding low lifted condensation levels. In addition, low level turning resulted in 0-1km SRH values of 100-200+ m2/s2 within an environment of 1000+ J/kg SBCAPE. With all of that in play, a pair of tornadoes were confirmed during the evening hours, before giving way to predominantly sub-severe storms and heavy rainfall. Heavy rainfall conditions were bolstered by strong 850mb/moisture flow throughout the event with precipitable water values approaching 1.5 to 1.75 inches.

Flood in MAHASKA, IOWA
From 08-OCT-18 08:41:00 to 09-OCT-18 09:00:00 (CST-6)
Location: EVANS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT reported Highway 92 closed due to brief flooding near Muchakinock Creek.

Flood in POWESHIEK, IOWA
From 09-OCT-18 17:00:00 to 10-OCT-18 00:45:00 (CST-6)
Location: GRINNELL
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 50.00K
Reported by: Emergency Manager

Emergency manager reported water over a few gravel roads near Grinnell north of Interstate 80 and other county roads closed near Searsboro due to flooding.

Flood in MARION, IOWA
From 09-OCT-18 15:09:00 to 10-OCT-18 00:45:00 (CST-6)
Location: KNOXVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT reported Highway 5 closed in both directions due to water over the road from English Creek, southeast of Knoxville.

Heavy Rain in DECATUR, IOWA
From 08-OCT-18 06:00:00 to 09-OCT-18 06:00:00 (CST-6)
Location: LAMONI
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Coop observer recorded heavy rainfall of 2.88 inches over the last 24 hours.

Heavy Rain in POWESHIEK, IOWA
From 08-OCT-18 08:00:00 to 09-OCT-18 08:00:00 (CST-6)
Location: GRINNELL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observer recorded heavy rainfall of 2.89 inches over the last 24 hours.

Heavy Rain in MARION, IOWA
From 08-OCT-18 07:00:00 to 09-OCT-18 07:00:00 (CST-6)
Location: KNOXVILLE ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Coop observer recorded heavy rainfall of 4.25 inches over the last 24 hours.

Flood in MARION, IOWA
From 09-OCT-18 17:00:00 to 10-OCT-18 00:45:00 (CST-6)
Location: PELLA
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 50.00K
Reported by: Emergency Manager

Emergency manager reported multiple gravel roads remain closed due to water over them or washed out throughout the county.

Flood in LUCAS, IOWA
From 09-OCT-18 12:06:00 to 10-OCT-18 00:45:00 (CST-6)
Location: DERBY
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT reported US 65 closed due to flooding between County Road H50 and US 34.

Tornado in GUTHRIE, IOWA
From 08-OCT-18 17:22:00 to 08-OCT-18 17:32:00 (CST-6)
Location: BAGLEY
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 1.00K
Reported by: NWS Storm Survey

QLCS tornado developed along the leading edge of the convection in northeast rural Guthrie County.  The tornado remained in cropland for its entire path producing plenty of crop damage along with topping trees in a few different groves.  The path was initially narrow but broadened as it continued northeast.  Only toward the end of the track did it narrow once more.  Damage path was also visible on high resolution satellite imagery.

Heavy Rain in APPANOOSE, IOWA
From 08-OCT-18 06:00:00 to 08-OCT-18 21:30:00 (CST-6)
Location: UDELL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported heavy rainfall of 2 inches from 6 am to 1030 pm local time.

Tornado in CLARKE, IOWA
From 08-OCT-18 18:53:00 to 08-OCT-18 19:01:00 (CST-6)
Location: WOODBURN
Tornado F-scale: EF1
Property damage: 15.00K
Crop damage: 2.00K
Reported by: Emergency Manager

The tornado developed south of McComb Street between 330th Avenue and 305th Avenue.  The tornado moved northeast across cropland and timberland producing EF1 damage at a old farmstead at the west end of Norman Street.  Additional crop damage was noted near the intersection of Pacific Street and 330th Avenue.  North of Pacific Street along 330th Avenue, extensive EF1 damage was noted to trees and a mobile home which had the midsection of the structure crushed by a falling tree branch.  Additional tree and outbuilding damage was noted to a farmstead just to the north.  The remainder of the path was in rural areas with little additional damage.

Thunderstorm Wind in CLARKE, IOWA
From 08-OCT-18 18:38:00 to 08-OCT-18 18:38:00 (CST-6)
Location: OSCEOLA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT passed along a report of a tree blocking one lane along Highway 69 south of Osceola. The tree was too big to move by hand. This is a delayed report.

Heavy Rain in MARION, IOWA
From 08-OCT-18 08:15:00 to 09-OCT-18 08:15:00 (CST-6)
Location: FLAGLER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station southeast of Knoxville recorded heavy rainfall of 3.01 inches over the last 24 hours.

Heavy Rain in MARION, IOWA
From 08-OCT-18 08:00:00 to 09-OCT-18 08:00:00 (CST-6)
Location: PELLA MUNI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Lake Red Rock mesonet station recorded heavy rainfall of 3.06 inches over the last 24 hours.

Heavy Rain in MARION, IOWA
From 08-OCT-18 08:26:00 to 09-OCT-18 08:26:00 (CST-6)
Location: PELLA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet station just north-northwest of Pella recorded heavy rainfall of 2.76 inches over the last 24 hours.

Heavy Rain in DECATUR, IOWA
From 08-OCT-18 05:53:00 to 09-OCT-18 05:53:00 (CST-6)
Location: (30I)LAMONI MUNI ARP
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Lamoni Municipal Airport ASOS recorded heavy rainfall of 2.65 inches over the last 24 hours.

Heavy Rain in LUCAS, IOWA
From 08-OCT-18 05:55:00 to 09-OCT-18 05:55:00 (CST-6)
Location: CHARITON MUNI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Chariton Municipal Airport recorded heavy rainfall of 2.72 inches over the last 24 hours.

Heavy Rain in MARION, IOWA
From 08-OCT-18 06:00:00 to 09-OCT-18 06:00:00 (CST-6)
Location: COLUMBIA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: COOP Observer

Coop observer recorded heavy rainfall of 3.40 inches over the last 24 hours.

Flood in DECATUR, IOWA
From 09-OCT-18 07:00:00 to 10-OCT-18 00:45:00 (CST-6)
Location: WESTERVILLE
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 50.00K
Reported by: Emergency Manager

Emergency manager reported two roads closed across the county due to culvert failure and approximately 10 culverts damaged from flooding.

Flood in JASPER, IOWA
From 09-OCT-18 17:00:00 to 10-OCT-18 00:45:00 (CST-6)
Location: SEARSBORO
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 50.00K
Reported by: Emergency Manager

Emergency manager reported a couple of roads with water over then near Sully.

Thunderstorm Wind in MAHASKA, IOWA
From 08-OCT-18 20:50:00 to 08-OCT-18 20:50:00 (CST-6)
Location: PEORIA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Six to 10 inches branches down from a tree in town. An off-duty NWS employee was traveling through town the day after the storm and say the branches down.