A frontal boundary was draped across areas just west of Iowa during the morning hours of June 30th, and slowly moved eastward into the state throughout the day. By the afternoon, it had made its way into central portions of the state, draping itself in a southwest to northeast fashion. Ahead of the front, the convective environment was ripe, with MUCAPE values in excess of 4000 J/kg and effective shear in the 30 to 40 kt range, with best values near the front.  While there was reason for concern with regards to severe weather, such has hail and damaging winds, there was also strong concern for an area of west-central, north central or central Iowa to receive heavy rainfall with the boundary placement, potential outflow boundary locations, low level jet initiation, and a very moist environment.  There was expectation for storms to be slow moving or training initially along the frontal boundary with propagation vectors opposing mean flow.
Initially storms fired up in the early afternoon across parts of northwest and north central Iowa in the very unstable environment, producing severe hail and wind damage. Fortunately, given their progressive nature, no water issues were seen with that round of convection. As the afternoon progressed, convection increased across northern areas, but remained quiet further south into central and southern Iowa. The initial northern convection pushed out an outflow boundary that made its way into the I-80 corridor, acting as another area for convective initiation. By the late evening, convection had fired up along the parent frontal boundary as well as portions of the aforementioned outflow boundary, producing marginally severe storms in most cases. By the time the low level jet kicked in, areas around Des Moines had already received a couple inches of rain, and now found the area in line for much more. Overall motion of storms was northeastward, but with nearly stationary frontal and outflow boundaries, backbuilding was induced by the low level jet, which resulted in copious amounts of heavy rainfall right on top of the Des Moines metro and surrounding areas. While some damaging wind was still ongoing, the primary concern was for heavy rainfall, flash flooding, and eventually a flash flood emergency. The Des Moines metro area took on widespread amounts of 6 or more inches, including a few reports of nearly 10 inches.  The main impacts revolved around flash flooding and the flash flood emergency with sewer systems and local streams absolutely overwhelmed. Dozens of vehicles were flooded or stranded, with numerous water rescues performed. Many streams were out of their banks, and an individual was swept away and killed during the flash flooding. One home had flooding and a gas leak that lead to an explosion of the home. Luckily all occupants had already been evacuated. Two streams with NWS stream gauge observations, Four Mile Creek and Walnut Creek, set all-time crest records.  Countless basements and businesses were flooded across the metro area and dozens of homes were completely flooded out on the southeast side where Four Mile Creek flooding was the worst. Two businesses had roof collapses from the heavy rain as well. The flash flooding and stream flooding continued into the overnight hours on July 1, so another entry is made in July 2018 for this event as well.

Heavy Rain in POLK, IOWA
From 30-JUN-18 16:00:00 to 30-JUN-18 19:48:00 (CST-6)
Location: LOVINGTON
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Public

Public reported heavy rainfall of 2.68 inches so far. Multiple cars were stalled on Meredith Ave with 8 inches of water rushing down 67th St to Meredith.

Thunderstorm Wind in GUTHRIE, IOWA
From 30-JUN-18 19:53:00 to 30-JUN-18 19:53:00 (CST-6)
Location: MENLO
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager reported branches down of at least 2 inches in diameter and a few up to 4 inches in diameter.

Flash Flood in STORY, IOWA
From 30-JUN-18 19:40:00 to 30-JUN-18 23:59:00 (CST-6)
Location: NEVADA
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 150.00K
Reported by: Emergency Manager

Emergency manager reported water over the road along 620th Ave approximately 3 miles south of Nevada.

Flash Flood in POLK, IOWA
From 30-JUN-18 19:49:00 to 30-JUN-18 23:59:00 (CST-6)
Location: URBANDALE
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Public

Public reported heavy rainfall of 2.68 inches measured at 8:47 pm. Multiple cars were also stalled on Meredith Ave with an estimated 8 inches of water rush down 67th St to Meredith.

Thunderstorm Wind in POLK, IOWA
From 30-JUN-18 20:06:00 to 30-JUN-18 20:06:00 (CST-6)
Location: URBANDALE
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported a 7 inch diameter tree branch down at 67th and Meredith.

Thunderstorm Wind in POLK, IOWA
From 30-JUN-18 20:08:00 to 30-JUN-18 20:08:00 (CST-6)
Location: LOVINGTON
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter, via social media, reported large tree branches of 6 to 10 inches in diameter down.

Flash Flood in POLK, IOWA
From 30-JUN-18 19:52:00 to 30-JUN-18 23:59:00 (CST-6)
Location: ANKENY
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Social Media

Public relayed a picture of water covering a residential street at NW 9th St and School St in Ankeny.

Flash Flood in POLK, IOWA
From 30-JUN-18 19:56:00 to 30-JUN-18 23:59:00 (CST-6)
Location: CLOVER HILLS
Flood cause: Heavy Rain
Property damage: 500.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter in Clive reported water running over the curbs on residential streets south of Hickman Dr.

Hail in POLK, IOWA
From 30-JUN-18 17:20:00 to 30-JUN-18 17:20:00 (CST-6)
Location: ANKENY
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported quarter sized hail.

Thunderstorm Wind in STORY, IOWA
From 30-JUN-18 17:50:00 to 30-JUN-18 17:50:00 (CST-6)
Location: ZEARING
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager relayed trained spotter reports of 60 to 70 mph winds.

Thunderstorm Wind in DALLAS, IOWA
From 30-JUN-18 17:56:00 to 30-JUN-18 17:56:00 (CST-6)
Location: MINBURN
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Fire department reported wind gusts to 60 mph.

Thunderstorm Wind in DALLAS, IOWA
From 30-JUN-18 17:57:00 to 30-JUN-18 17:57:00 (CST-6)
Location: ADEL
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Fire department reported minor damage to trees and power transformers.

Thunderstorm Wind in TAMA, IOWA
From 30-JUN-18 18:24:00 to 30-JUN-18 18:24:00 (CST-6)
Location: TRAER MUNI ARPT
Magnitude: 56.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported trees down in Traer.

Hail in UNION, IOWA
From 30-JUN-18 18:40:00 to 30-JUN-18 18:40:00 (CST-6)
Location: CRESTON ARPT
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager reported quarter sized hail.

Heavy Rain in STORY, IOWA
From 30-JUN-18 16:30:00 to 30-JUN-18 18:44:00 (CST-6)
Location: COLLINS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported heavy rainfall of about 2 inches so far.

Flash Flood in STORY, IOWA
From 30-JUN-18 18:45:00 to 30-JUN-18 23:59:00 (CST-6)
Location: NEVADA
Flood cause: Heavy Rain
Property damage: 10.00K
Crop damage: 25.00K
Reported by: Law Enforcement

Law enforcement reported water running over the road at 250th Ave and 650th Street.

Flash Flood in DALLAS, IOWA
From 30-JUN-18 19:00:00 to 30-JUN-18 23:59:00 (CST-6)
Location: DALLAS CENTER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported standing water and partially blocked roadways on the west side of Dallas Center.

Heavy Rain in STORY, IOWA
From 30-JUN-18 16:30:00 to 30-JUN-18 19:00:00 (CST-6)
Location: MAXWELL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

The Maxwell LARC recorded 3.8 inches of heavy rainfall so far today.

Flash Flood in DALLAS, IOWA
From 30-JUN-18 19:05:00 to 30-JUN-18 23:59:00 (CST-6)
Location: DALLAS CENTER
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 50.00K
Reported by: Fire Department/Rescue

Local fire department reported numerous roads in town barely passable or impassable, as well as a portion of Highway 44 west of town with water over the road.

Heavy Rain in STORY, IOWA
From 30-JUN-18 16:30:00 to 30-JUN-18 19:05:00 (CST-6)
Location: COLLINS
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

KWWL relayed a viewer report of heavy rainfall of about 3.5 inches so far.

Flash Flood in STORY, IOWA
From 30-JUN-18 19:10:00 to 30-JUN-18 23:59:00 (CST-6)
Location: MAXWELL
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 50.00K
Reported by: Law Enforcement

Law enforcement reported flash flooding around Maxwell with numerous roads reported as having water running over them.

Heavy Rain in POLK, IOWA
From 30-JUN-18 16:30:00 to 30-JUN-18 21:22:00 (CST-6)
Location: LOVINGTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported heavy rainfall of 7.32 inches at 67th and Meredith in Urbandale as of 10:22 pm.

Heavy Rain in POLK, IOWA
From 30-JUN-18 18:30:00 to 30-JUN-18 21:28:00 (CST-6)
Location: SAYDELL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported heavy rainfall of about 5.5 inches since 7:30 pm this evening.

Heavy Rain in POLK, IOWA
From 30-JUN-18 16:30:00 to 30-JUN-18 21:44:00 (CST-6)
Location: JOHNSTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Amateur radio operator reported heavy rainfall of 7.1 inches in Johnston as of 10:43 pm.

Thunderstorm Wind in HUMBOLDT, IOWA
From 30-JUN-18 13:34:00 to 30-JUN-18 13:34:00 (CST-6)
Location: RENWICK
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

Public reported several large trees down in town.

Hail in POCAHONTAS, IOWA
From 30-JUN-18 12:38:00 to 30-JUN-18 12:38:00 (CST-6)
Location: ROLFE
Magnitude: 1.00 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported quarter sized hail.

Hail in POCAHONTAS, IOWA
From 30-JUN-18 12:51:00 to 30-JUN-18 12:51:00 (CST-6)
Location: ROLFE
Magnitude: 1.25 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported half dollar sized hail.

Thunderstorm Wind in HUMBOLDT, IOWA
From 30-JUN-18 13:15:00 to 30-JUN-18 13:15:00 (CST-6)
Location: RUTLAND
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Trained spotter reported corn laid flat by wind.

Thunderstorm Wind in HUMBOLDT, IOWA
From 30-JUN-18 13:20:00 to 30-JUN-18 13:20:00 (CST-6)
Location: RUTLAND
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 10.00K
Reported by: Trained Spotter

Trained spotter reported large branches down along with nickel sized hail.

Thunderstorm Wind in WRIGHT, IOWA
From 30-JUN-18 13:46:00 to 30-JUN-18 13:46:00 (CST-6)
Location: EAGLE GROVE
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported tree damage and one power line down outside of town.

Thunderstorm Wind in WRIGHT, IOWA
From 30-JUN-18 13:55:00 to 30-JUN-18 13:55:00 (CST-6)
Location: GOLDFIELD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported tree limbs down due to thunderstorm winds.

Flash Flood in POLK, IOWA
From 30-JUN-18 19:57:00 to 30-JUN-18 23:59:00 (CST-6)
Location: ELKHART
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported that Delaware Ave was under water north of NE 36th St in Ankeny.

Heavy Rain in POLK, IOWA
From 30-JUN-18 19:00:00 to 30-JUN-18 21:41:00 (CST-6)
Location: ALTOONA
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported heavy rainfall of 6.5 inches in Altoona since 8 pm.

Flash Flood in POLK, IOWA
From 30-JUN-18 21:49:00 to 30-JUN-18 23:59:00 (CST-6)
Location: LOVINGTON
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported street and guard rails starting to be washed away with the ground deteriorating.

Heavy Rain in BLACK HAWK, IOWA
From 30-JUN-18 16:15:00 to 30-JUN-18 22:12:00 (CST-6)
Location: WATERLOO
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

KWWL reported heavy rainfall of 2.05 inches so far.

Heavy Rain in POLK, IOWA
From 30-JUN-18 16:30:00 to 30-JUN-18 22:24:00 (CST-6)
Location: SAYDELL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported heavy rainfall of 7.50 inches near Saylorville in rural Polk County as of 11:24 pm.

Thunderstorm Wind in POLK, IOWA
From 30-JUN-18 20:30:00 to 30-JUN-18 20:30:00 (CST-6)
Location: ASHAWA
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter, via social media, shared a photo of a large tree branch around 6 to 10 inches in diameter down.

Flash Flood in POLK, IOWA
From 30-JUN-18 22:00:00 to 30-JUN-18 23:59:00 (CST-6)
Location: URBANDALE
Flood cause: Heavy Rain
Property damage: 300.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A home was flooded by Rocklyn Creek which caused a divider wall in the duplex to fail and collapse. Two residents were stuck in side and swam to safety through a downstairs window. The remaining residents were evacuated. Soon after the home exploded due to a gas leak when the wall collapsed. The explosion damaged a few nearby homes as well.

Lightning in POLK, IOWA
From 30-JUN-18 20:00:00 to 30-JUN-18 20:00:00 (CST-6)
Location: CAPITOL HGTS
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A lightning strike caused a garage fire damaging a portion of the garage.

Flood in POLK, IOWA
From 30-JUN-18 22:30:00 to 30-JUN-18 23:59:00 (CST-6)
Location: CAPITOL HGTS
Flood cause: Heavy Rain
Property damage: 2.00M
Crop damage: 50.00K
Reported by: Official NWS Observations

Fourmile Creek at Easton Blvd crested at 17.47 feet on 1 July 2018 at 1030Z.

Flood in POLK, IOWA
From 30-JUN-18 20:30:00 to 30-JUN-18 23:59:00 (CST-6)
Location: WINDSOR HGTS
Flood cause: Heavy Rain
Property damage: 2.00M
Crop damage: 0.00K
Reported by: Official NWS Observations

Walnut Creek at Des Moines 63rd Street crested at 17.37 feet on 1 July 2018 at 1130Z.

Thunderstorm Wind in HANCOCK, IOWA
From 30-JUN-18 14:07:00 to 30-JUN-18 14:07:00 (CST-6)
Location: GOODELL
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported large tree limbs down all over town.

Hail in CERRO GORDO, IOWA
From 30-JUN-18 14:15:00 to 30-JUN-18 14:15:00 (CST-6)
Location: CLEAR LAKE
Magnitude: 1.50 
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported ping pong ball sized hail.

Flash Flood in STORY, IOWA
From 30-JUN-18 20:02:00 to 30-JUN-18 23:59:00 (CST-6)
Location: COLLINS
Flood cause: Heavy Rain
Property damage: 50.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager relayed that a citizen estimated around 4 inches of water over Highway 65 at 4th St in Collins.

Thunderstorm Wind in MADISON, IOWA
From 30-JUN-18 20:03:00 to 30-JUN-18 20:03:00 (CST-6)
Location: WINTERSET
Magnitude: 61.00 EG
Property damage: 60.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported a roof blown off a house and a large tree down in town.

Thunderstorm Wind in GUTHRIE, IOWA
From 30-JUN-18 20:09:00 to 30-JUN-18 20:09:00 (CST-6)
Location: FANSLERS
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported wind gusts to around 60 mph.

Heavy Rain in POLK, IOWA
From 30-JUN-18 16:00:00 to 30-JUN-18 20:13:00 (CST-6)
Location: JOHNSTON
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported heavy rainfall of 5.6 inches so far.

Flash Flood in POLK, IOWA
From 30-JUN-18 20:22:00 to 30-JUN-18 23:59:00 (CST-6)
Location: WEST DES MOINES
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported that 63rd and Grand near West Des Moines was underwater. Water rescues were performed at this location as well.

Flash Flood in POLK, IOWA
From 30-JUN-18 20:25:00 to 30-JUN-18 23:59:00 (CST-6)
Location: ELKHART
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported multiple vehicles stalled along Delaware Ave in Ankeny.

Flash Flood in POLK, IOWA
From 30-JUN-18 20:28:00 to 30-JUN-18 23:59:00 (CST-6)
Location: ENTERPRISE
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported UPS vehicle rescues have taken place, with water about chest deep in some areas.

Flash Flood in POLK, IOWA
From 30-JUN-18 20:39:00 to 30-JUN-18 23:59:00 (CST-6)
Location: ELKHART
Flood cause: Heavy Rain
Property damage: 1.00M
Crop damage: 500.00K
Reported by: Emergency Manager

Emergency manager reported multiple water rescues across Ankeny, Johnston, Des Moines and Urbandale. Vehicles were stalled out in street flooding with water half way up the doors of some cars.

Flash Flood in POLK, IOWA
From 30-JUN-18 20:42:00 to 30-JUN-18 23:59:00 (CST-6)
Location: RIDER
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported water covering the road in the area.

Heavy Rain in POLK, IOWA
From 30-JUN-18 16:00:00 to 30-JUN-18 20:44:00 (CST-6)
Location: URBANDALE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported heavy rainfall of 7.30 inches so far in Urbandale.

Heavy Rain in POLK, IOWA
From 30-JUN-18 16:30:00 to 30-JUN-18 21:15:00 (CST-6)
Location: ANKENY
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported estimated heavy rainfall of 10 inches on the north side of Ankeny as of 10:15 pm.

Flash Flood in POLK, IOWA
From 30-JUN-18 19:11:00 to 30-JUN-18 23:59:00 (CST-6)
Location: ORALABOR
Flood cause: Heavy Rain
Property damage: 200.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported flooding along Rock Creek near NW 13th St in Ankeny.

Flash Flood in BLACK HAWK, IOWA
From 30-JUN-18 19:20:00 to 30-JUN-18 23:59:00 (CST-6)
Location: WATERLOO
Flood cause: Heavy Rain
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Broadcast Media

KWWL reported flash flooding along 4th St in downtown Waterloo.

Flash Flood in POLK, IOWA
From 30-JUN-18 19:27:00 to 30-JUN-18 23:59:00 (CST-6)
Location: ELKHART
Flood cause: Heavy Rain
Property damage: 250.00K
Crop damage: 50.00K
Reported by: Social Media

Public relayed a picture of flooding along Fourmile Creek.

Heavy Rain in STORY, IOWA
From 30-JUN-18 16:45:00 to 30-JUN-18 19:28:00 (CST-6)
Location: MAXWELL
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public reported heavy rainfall of about 5 inches since 5:45 pm today, and that there was standing water in the area.