The events of the day came in two waves. An initial wave of heavy rainfall ahead of the surface low, and then severe weather near the triple point in northern Iowa as the surface low crossed Iowa.
For wave one, southern Iowa, storms were induced overnight of the 23rd into the 24th across eastern Kansas and made its way ENE towards and across southern Iowa during the very early morning hours of the 24th. Fortunately, given the timing, storms were elevated and able to remain sub-severe. Instead, with precipitable water values approaching two inches, heavy rainfall was experienced even with the progressive nature of the storms.
Wave two took place across northern Iowa in and around the surface low triple point as it moved across the state. Within the warm sector and near the boundaries, the severe weather potential and supporting variables were present. Support for severe weather included SBCAPE of 3000+ J/kg, 30-40+ kts of effective bulk shear, and 100+ m2/s2 effective storm relative helicity. In the end, fortunately, generally a single cluster of strong storms formed and moved across northern Iowa. Severe weather produced included large hail to about golf ball size, damaging winds, and a funnel cloud report.

Heavy Rain in APPANOOSE, IOWA
From 24-AUG-18 00:00:00 to 24-AUG-18 04:30:00 (CST-6)
Location: FORBUSH
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported heavy rainfall of 2.06 inches.

Heavy Rain in DAVIS, IOWA
From 23-AUG-18 08:00:00 to 24-AUG-18 08:00:00 (CST-6)
Location: FLORIS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observer recorded heavy rainfall over the last 24 hours.

Heavy Rain in DAVIS, IOWA
From 23-AUG-18 08:00:00 to 24-AUG-18 08:00:00 (CST-6)
Location: FLORIS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observer recorded heavy rainfall of 2.11 inches over the last 24 hours.

Heavy Rain in DAVIS, IOWA
From 23-AUG-18 08:00:00 to 24-AUG-18 08:00:00 (CST-6)
Location: ASH GROVE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observer recorded heavy rainfall of 2.65 inches over the last 24 hours.

Heavy Rain in WAPELLO, IOWA
From 23-AUG-18 08:00:00 to 24-AUG-18 08:00:00 (CST-6)
Location: DAHLONEGA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observer recorded heavy rainfall of 2.36 inches over the last 24 hours.

Heavy Rain in WAPELLO, IOWA
From 23-AUG-18 08:08:00 to 24-AUG-18 08:08:00 (CST-6)
Location: AGENCY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: CoCoRaHS

CoCoRaHS observer recorded heavy rainfall of 2.07 inches over the last 24 hours.

Funnel Cloud in HANCOCK, IOWA
From 24-AUG-18 17:06:00 to 24-AUG-18 17:06:00 (CST-6)
Location: HAYFIELD
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter called in rotation with the storm and an associated funnel cloud.

Hail in CERRO GORDO, IOWA
From 24-AUG-18 17:43:00 to 24-AUG-18 17:43:00 (CST-6)
Location: CLEAR LAKE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported lots of quarter sized hail.

Hail in CERRO GORDO, IOWA
From 24-AUG-18 17:44:00 to 24-AUG-18 17:44:00 (CST-6)
Location: (MCW)MASON CITY MUNI
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported up to quarter sized hail.

Hail in CERRO GORDO, IOWA
From 24-AUG-18 17:45:00 to 24-AUG-18 17:45:00 (CST-6)
Location: CLEAR LAKE LAKE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public relayed a picture of hail larger than quarters via twitter.

Hail in CERRO GORDO, IOWA
From 24-AUG-18 18:10:00 to 24-AUG-18 18:10:00 (CST-6)
Location: MASON CITY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported nickel to quarter sized hail.

Hail in KOSSUTH, IOWA
From 24-AUG-18 16:28:00 to 24-AUG-18 16:35:00 (CST-6)
Location: MAYLAND ARPT
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 50.00K
Reported by: Trained Spotter

Trained spotter reported 50 to 60 percent of bean leaves stripped from the hail. Hail lasted from roughly 528 to 535 pm, and was mainly dime size but as large as half dollars. Heavy rain and winds estimated to 50 mph were occurring as well.

Hail in CERRO GORDO, IOWA
From 24-AUG-18 17:50:00 to 24-AUG-18 17:50:00 (CST-6)
Location: CLEAR LAKE
Magnitude: 1.75 
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Local media relayed a public social media picture of large hail, estimated around golf ball in size.  Time estimated from radar.

Thunderstorm Wind in CERRO GORDO, IOWA
From 24-AUG-18 17:50:00 to 24-AUG-18 17:50:00 (CST-6)
Location: MASON CITY
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Local 911 call center reported a power line down on a tree and an associated fire along Birch Dr. Time estimated from radar.

Hail in CERRO GORDO, IOWA
From 24-AUG-18 17:56:00 to 24-AUG-18 17:56:00 (CST-6)
Location: CLEAR LAKE
Magnitude: 1.25 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported ongoing quarter to half dollar sized hail.

Lightning in CERRO GORDO, IOWA
From 24-AUG-18 17:59:00 to 24-AUG-18 17:59:00 (CST-6)
Location: CLEAR LAKE
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Local 911 call center reported a boat struck by lightning on the shore of Clear Lake. Fire also reported, but magnitude unknown. Other reports of a house struck by lightning in the area as well.  Time estimated.