Two rounds of convection moved across Iowa in quick succession beginning in the pre-dawn hours of July 12th. This first was an area of convection that developed along an elevated boundary into northwest Iowa. While this area of storms mainly remained sub-severe, severe hail did fall across central Iowa near 6 am. At the same time a MCS moved out of the Dakotas and into western Iowa, moving quickly and eventually merging with the first area of storms. This second round developed into a line of storms with winds gusting up to 70 mph, fueled by the low level jet. Orientation of 0-3 km shear was favorable for quick spin-ups and two weaker tornadoes did form in Cass county that morning. With deep warm cloud layers over 4000 meters and precipitable water nearing 2, areas that received rain in both rounds received two to four inches by the time storms ended late in the morning. An isolated pocket of four to six inches fell in Greene and Boone counties, creating flash flooding in the area.

Tornado in CASS, IOWA
From 12-JUL-23 05:38:00 to 12-JUL-23 05:40:00 (CST-6)
Location: MARNE
Tornado F-scale: EF0
Property damage: 0.00K
Crop damage: 1.00K
Reported by: Official NWS Observations

Tornado was indicated by a Correlation Coefficient depression on radar and also verified through high resolution satellite imagery north of Marne.  The tornado remained in mostly open cropland although some EF0 tree damage was done to a tree line along the edge of one of the fields.

Tornado in CASS, IOWA
From 12-JUL-23 05:39:00 to 12-JUL-23 05:42:00 (CST-6)
Location: MARNE
Tornado F-scale: EF0
Property damage: 5.00K
Crop damage: 1.00K
Reported by: Emergency Manager

Damage from this tornado was relayed by the Cass County Emergency Manager and the path was also found in high resolution satellite imagery.  Some minor damage to trees and outbuildings occurred at one farmstead east of Marne with the remainder of the path through open cropland.

Hail in WARREN, IOWA
From 12-JUL-23 05:58:00 to 12-JUL-23 05:58:00 (CST-6)
Location: NORWALK
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Thunderstorm Wind in ADAMS, IOWA
From 12-JUL-23 06:00:00 to 12-JUL-23 06:00:00 (CST-6)
Location: LINCOLN CENTER
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Delayed report, peak gust of 65 mph at personal weather station.

Thunderstorm Wind in ADAMS, IOWA
From 12-JUL-23 06:12:00 to 12-JUL-23 06:12:00 (CST-6)
Location: CORNING
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public report of 70 mph wind gust.

Thunderstorm Wind in ADAIR, IOWA
From 12-JUL-23 06:17:00 to 12-JUL-23 06:17:00 (CST-6)
Location: FONTANELLE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public report of 65 mph wind gust.

Thunderstorm Wind in UNION, IOWA
From 12-JUL-23 06:20:00 to 12-JUL-23 06:20:00 (CST-6)
Location: CROMWELL
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Delayed report of tree limbs down.

Thunderstorm Wind in BOONE, IOWA
From 12-JUL-23 06:46:00 to 12-JUL-23 06:46:00 (CST-6)
Location: BOONE MUNI ARPT
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Medium sized tree down and blocking the road. Delayed report, time estimated from radar.

Thunderstorm Wind in UNION, IOWA
From 12-JUL-23 06:50:00 to 12-JUL-23 06:50:00 (CST-6)
Location: CRESTON
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Tree snapped. Report via social media.

Thunderstorm Wind in UNION, IOWA
From 12-JUL-23 06:55:00 to 12-JUL-23 06:55:00 (CST-6)
Location: LORIMOR
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Trees down on the road. Delayed report, time estimated by radar.

Heavy Rain in BOONE, IOWA
From 12-JUL-23 03:00:00 to 12-JUL-23 08:47:00 (CST-6)
Location: BOONE MUNI ARPT
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 4.40 inches.

Heavy Rain in BOONE, IOWA
From 12-JUL-23 03:00:00 to 12-JUL-23 08:49:00 (CST-6)
Location: NAPIER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 3.63 inches.

Heavy Rain in POLK, IOWA
From 12-JUL-23 04:00:00 to 12-JUL-23 08:52:00 (CST-6)
Location: RIDER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 2.51 inches.

Heavy Rain in POLK, IOWA
From 12-JUL-23 04:00:00 to 12-JUL-23 08:59:00 (CST-6)
Location: FT DES MOINES
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 2.25 inches.

Heavy Rain in STORY, IOWA
From 12-JUL-23 04:00:00 to 12-JUL-23 09:15:00 (CST-6)
Location: HUXLEY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Event total of 3.50 inches.

Heavy Rain in POCAHONTAS, IOWA
From 12-JUL-23 05:00:00 to 12-JUL-23 09:41:00 (CST-6)
Location: POCAHONTAS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 2.20 inches.

Heavy Rain in STORY, IOWA
From 12-JUL-23 04:00:00 to 12-JUL-23 09:52:00 (CST-6)
Location: ONTARIO
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Event total of 3.30 inches.

Heavy Rain in WEBSTER, IOWA
From 12-JUL-23 04:30:00 to 12-JUL-23 10:14:00 (CST-6)
Location: GOWRIE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 2.75 inches.

Heavy Rain in GREENE, IOWA
From 12-JUL-23 04:00:00 to 12-JUL-23 11:42:00 (CST-6)
Location: DANA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 6.20 inches.

Heavy Rain in CARROLL, IOWA
From 12-JUL-23 02:00:00 to 12-JUL-23 08:00:00 (CST-6)
Location: LIDDERDALE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 3.00 inches.

Heavy Rain in MARSHALL, IOWA
From 12-JUL-23 03:00:00 to 12-JUL-23 12:24:00 (CST-6)
Location: STATE CENTER
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Event total of 2.95 inches.

Heavy Rain in BOONE, IOWA
From 12-JUL-23 03:00:00 to 12-JUL-23 08:15:00 (CST-6)
Location: BOONE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Event total of 4.50 inches.

Heavy Rain in POLK, IOWA
From 12-JUL-23 04:00:00 to 12-JUL-23 09:00:00 (CST-6)
Location: AVON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Event total of 3.00 inches.

Thunderstorm Wind in UNION, IOWA
From 12-JUL-23 06:25:00 to 12-JUL-23 06:25:00 (CST-6)
Location: CRESTON
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Tree limbs down. Delayed report, time estimated by radar.

Flash Flood in BOONE, IOWA
From 12-JUL-23 07:15:00 to 12-JUL-23 10:15:00 (CST-6)
Location: BOONE MUNI ARPT
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Water flowing through the grounds of Boone Speedway.