The atmosphere was juiced so to speak ahead of a cold front sliding into the region. MUCAPE values very quickly approached and exceeded 4000 J/kg by mid-morning. With the cold front and previous storm outflows the impetus for new convection, discrete storms were not expected, with the prevailing storm type being the linear or quasi-linear convective system (QLCS) variety. Additional support for the QLCS mode was seen with, once again the cold frontal and outflow forcing, highly unstable atmosphere, and little to no convective inhibition.  Additional support for strong winds was seen with DCAPE values in excess of 1500 J/kg across much of the area  Once a system began to produce a decent cold pool, there would be little to prevent it from progressing.
That was evident in Iowa as two distinct QLCSs moved through. First in the morning hours across northern Iowa, and second during the late morning through evening hours from central Iowa and on toward south central and southeast Iowa. In both cases, damaging winds widely prevailed. Across northern Iowa the gust front roared out ahead of the line of convection, continuing to produce severe wind reports in areas of no storms well to the south and east. In central and southeast Iowa, widespread reports of 60 to 70 mph winds and various tree damage (from large limbs to entire trees) were received along a path from roughly Perry, IA through Ottumwa, IA.

Thunderstorm Wind in JASPER, IOWA
From 20-JUL-19 17:11:00 to 20-JUL-19 17:11:00 (CST-6)
Location: SULLY
Magnitude: 56.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported a large 1.5 foot diameter tree down in front of a business in Sully.  Time estimated from radar.

Thunderstorm Wind in MARION, IOWA
From 20-JUL-19 17:15:00 to 20-JUL-19 17:15:00 (CST-6)
Location: KNOXVILLE ARPT
Magnitude: 59.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Knoxville Municipal Airport AWOS recorded a 68 mph wind gust.

Thunderstorm Wind in BREMER, IOWA
From 20-JUL-19 11:28:00 to 20-JUL-19 11:28:00 (CST-6)
Location: SUMNER
Magnitude: 60.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Some inflatables were blown away from a town celebration. Two injuries were sustained at the town celebration from outdoor flying objects. There were no thunderstorms in the area, as they were to the north, but the strong gust front from the storms up north produced the damage.

Thunderstorm Wind in FRANKLIN, IOWA
From 20-JUL-19 10:37:00 to 20-JUL-19 10:37:00 (CST-6)
Location: HAMPTON
Magnitude: 52.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager reported three large trees down in town and estimate 60 mph winds.

Thunderstorm Wind in MARION, IOWA
From 20-JUL-19 17:21:00 to 20-JUL-19 17:21:00 (CST-6)
Location: PELLA
Magnitude: 57.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Pella RWIS on Hwy 163 recorded a 66 mph wind gust.

Thunderstorm Wind in GUTHRIE, IOWA
From 20-JUL-19 17:21:00 to 20-JUL-19 17:21:00 (CST-6)
Location: HERNDON
Magnitude: 61.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Guthrie County emergency manager reported large trees down in Yale, blocking several streets.

Thunderstorm Wind in FRANKLIN, IOWA
From 20-JUL-19 10:38:00 to 20-JUL-19 10:38:00 (CST-6)
Location: HAMPTON MUNI ARPT
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public shared an image of a large tree limb down at the Franklin County Fairgrounds. Time estimated from radar.

Thunderstorm Wind in WARREN, IOWA
From 20-JUL-19 16:43:00 to 20-JUL-19 16:43:00 (CST-6)
Location: INDIANOLA
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT reports tree and power line damage along Highway 92. Time estimated from radar.

Thunderstorm Wind in WAPELLO, IOWA
From 20-JUL-19 18:33:00 to 20-JUL-19 18:33:00 (CST-6)
Location: OTTUMWA
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

Trained spotter reported a large tree limb down and a power line down near the tree limb.

Thunderstorm Wind in WARREN, IOWA
From 20-JUL-19 16:45:00 to 20-JUL-19 16:45:00 (CST-6)
Location: INDIANOLA
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported a large tree blown over and a smaller tree split in half. Some minor street flooding also reported.

Thunderstorm Wind in WAPELLO, IOWA
From 20-JUL-19 18:25:00 to 20-JUL-19 18:25:00 (CST-6)
Location: OTTUMWA
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported a tree uprooted on the south side of Ottumwa. Time estimated from radar.

Thunderstorm Wind in EMMET, IOWA
From 20-JUL-19 09:01:00 to 20-JUL-19 09:01:00 (CST-6)
Location: ESTHERVILLE ARPT
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Estherville Municipal Airport ASOS recorded a 64 mph wind gust.

Thunderstorm Wind in EMMET, IOWA
From 20-JUL-19 09:03:00 to 20-JUL-19 09:03:00 (CST-6)
Location: ESTHERVILLE ARPT
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Estherville Municipal Airport ASOS recorded a 64 mph wind gust.

Thunderstorm Wind in MARION, IOWA
From 20-JUL-19 17:10:00 to 20-JUL-19 17:10:00 (CST-6)
Location: KNOXVILLE
Magnitude: 50.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported two 4 inch diameter maple branches down. Also noted multiple reports of tree damage across town. Time estimated from radar.

Thunderstorm Wind in BREMER, IOWA
From 20-JUL-19 11:13:00 to 20-JUL-19 11:13:00 (CST-6)
Location: WAVERLY
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A large tree limb nearly 1 foot in diameter was broken from the gust front. There was no thunderstorm, as they were to the north, but the strong gust front from the storms up north produced the damage.

Thunderstorm Wind in KOSSUTH, IOWA
From 20-JUL-19 09:37:00 to 20-JUL-19 09:37:00 (CST-6)
Location: WHITTEMORE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported estimated 60 mph gusts. A few larger tree limbs were reported down, with several smaller branches and twigs down as well.

Thunderstorm Wind in HANCOCK, IOWA
From 20-JUL-19 09:55:00 to 20-JUL-19 09:55:00 (CST-6)
Location: MILLER
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Forest City Municipal Airport AWOS recorded a 60 mph wind gust.

Thunderstorm Wind in KOSSUTH, IOWA
From 20-JUL-19 09:38:00 to 20-JUL-19 09:38:00 (CST-6)
Location: ALGONA
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported several larger tree limbs down in Algona.

Thunderstorm Wind in CERRO GORDO, IOWA
From 20-JUL-19 10:26:00 to 20-JUL-19 10:26:00 (CST-6)
Location: MASON CITY
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Public

KIMT TV viewer shared a photo of a large tree limb snapped in Mason City. Looked to be at least 8 inches in diameter.

Thunderstorm Wind in BREMER, IOWA
From 20-JUL-19 11:18:00 to 20-JUL-19 11:18:00 (CST-6)
Location: FREDERIKA
Magnitude: 60.00 EG
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous trees blown down in the town. One home had a tree go through the roof. There were no thunderstorms in the area, as they were to the north, but the strong gust front from the storms up north produced the damage.

Thunderstorm Wind in WINNEBAGO, IOWA
From 20-JUL-19 09:58:00 to 20-JUL-19 09:58:00 (CST-6)
Location: FOREST CITY
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several spotters reported tree limbs, about 3 to 4 inches in diameter, have been downed.

Thunderstorm Wind in HANCOCK, IOWA
From 20-JUL-19 10:06:00 to 20-JUL-19 10:06:00 (CST-6)
Location: GARNER
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public relayed picture of 5 inch tree limbs downed. Time estimated from radar.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 15:35:00 to 20-JUL-19 15:35:00 (CST-6)
Location: PERRY
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Amateur radio reported a large tree down just outside of town. Passed on from Perry Police. Time estimated from radar.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 16:00:00 to 20-JUL-19 16:00:00 (CST-6)
Location: DALLAS MINE
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Amateur radio reported 4 inch tree limbs down at F31 and R22. Time estimated from radar.

Thunderstorm Wind in BREMER, IOWA
From 20-JUL-19 11:10:00 to 20-JUL-19 11:10:00 (CST-6)
Location: WAVERLY
Magnitude: 60.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Numerous tents on the fairgrounds were blown down with people in them causing some injuries. In another place in town a woman had a broken arm when a tree fell on her while mowing the lawn. Several trees fell across the area with some additional injuries. There was no thunderstorm in the area, as they were to the north, but the strong gust front from the storms up north produced the damage.

Thunderstorm Wind in HANCOCK, IOWA
From 20-JUL-19 10:06:00 to 20-JUL-19 10:06:00 (CST-6)
Location: GARNER
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public relayed picture of large tree limb, about 10 inches in diameter, broken in Garner.

Thunderstorm Wind in WRIGHT, IOWA
From 20-JUL-19 10:15:00 to 20-JUL-19 10:15:00 (CST-6)
Location: CLARION ARPT
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Clarion Municipal Airport AWOS recorded 58 mph wind gust.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 16:02:00 to 20-JUL-19 16:02:00 (CST-6)
Location: DALLAS CENTER
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Amateur radio reported a large tree down along Vine St. Time estimated from radar.

Thunderstorm Wind in CERRO GORDO, IOWA
From 20-JUL-19 10:20:00 to 20-JUL-19 10:20:00 (CST-6)
Location: (MCW)MASON CITY MUNI
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Mason City Municipal Airport recorded a 61 mph wind gust.

Thunderstorm Wind in FRANKLIN, IOWA
From 20-JUL-19 10:38:00 to 20-JUL-19 10:38:00 (CST-6)
Location: HAMPTON
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

Public shared a picture of downed tree limbs, about 2 to 3 inches in diameter, and tents ripped apart. Wind gusts were estimated to be between 50 and 60 mph.

Thunderstorm Wind in POLK, IOWA
From 20-JUL-19 16:15:00 to 20-JUL-19 16:15:00 (CST-6)
Location: FARRAR
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported a resident shed tipped over. Time estimated from radar.

Thunderstorm Wind in POLK, IOWA
From 20-JUL-19 16:18:00 to 20-JUL-19 16:18:00 (CST-6)
Location: SWANWOOD
Magnitude: 56.00 EG
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT reported portable message boards blown over. Time estimated from radar.

Thunderstorm Wind in BREMER, IOWA
From 20-JUL-19 11:13:00 to 20-JUL-19 11:13:00 (CST-6)
Location: WAVERLY
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

KWWL viewer shared pictures of tree damage, branches 2 to 3 inches in diameter downed, in Waverly. Time estimated from radar.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 16:00:00 to 20-JUL-19 16:00:00 (CST-6)
Location: DALLAS CENTER
Magnitude: 56.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Dallas Center Fire reported a pole barn lost its roof at the feed lot. Time estimated from radar.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 16:20:00 to 20-JUL-19 16:20:00 (CST-6)
Location: GRANGER
Magnitude: 56.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Amateur radio reported utility wires down.

Thunderstorm Wind in POLK, IOWA
From 20-JUL-19 16:24:00 to 20-JUL-19 16:24:00 (CST-6)
Location: SWANWOOD
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT reported trees down at the Iowa DOT facility in Ankeny, including small 4 to 6 inch diameter trees snapped and blown down. This is a delayed report and time estimated from radar.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 16:02:00 to 20-JUL-19 16:02:00 (CST-6)
Location: GRANGER
Magnitude: 61.00 EG
Property damage: 20.00K
Crop damage: 0.00K
Reported by: Fire Department/Rescue

Local fire department reported power poles down. Time estimated from radar.

Thunderstorm Wind in POLK, IOWA
From 20-JUL-19 16:15:00 to 20-JUL-19 16:15:00 (CST-6)
Location: ANKENY
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Polk County Emergency Management reported 4 inch tree branches down.

Thunderstorm Wind in GUTHRIE, IOWA
From 20-JUL-19 17:10:00 to 20-JUL-19 17:10:00 (CST-6)
Location: HERNDON
Magnitude: 61.00 EG
Property damage: 15.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager reported numerous trees down at the property. The largest was about 14 inches in diameter. A tree branch left a hole in the roof of the residence. Time estimated from radar.

Hail in POLK, IOWA
From 20-JUL-19 16:20:00 to 20-JUL-19 16:20:00 (CST-6)
Location: FARRAR
Magnitude: 0.75 
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported penny sized hail, as well as sapling trees snapped.

Thunderstorm Wind in POLK, IOWA
From 20-JUL-19 16:23:00 to 20-JUL-19 16:23:00 (CST-6)
Location: SWANWOOD
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported a large 6 to 8 inch tree branch snapped. This is a delayed report and time estimated from radar.

Thunderstorm Wind in MARION, IOWA
From 20-JUL-19 17:10:00 to 20-JUL-19 17:10:00 (CST-6)
Location: PELLA MUNI ARPT
Magnitude: 56.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Broadcast Media

KNIA/KRLS reported power outages across the county, as well as a tree down at a campground near Red Rock, possibly trapping someone in a vehicle. Report came in via social media.

Thunderstorm Wind in MAHASKA, IOWA
From 20-JUL-19 17:40:00 to 20-JUL-19 17:40:00 (CST-6)
Location: OSKALOOSA
Magnitude: 56.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Mahaska County emergency manager reported many instances of tree damage and power outages across the county. Time estimated from radar, via the center of the county.

Thunderstorm Wind in WARREN, IOWA
From 20-JUL-19 16:50:00 to 20-JUL-19 16:50:00 (CST-6)
Location: COOL
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter estimated 50 to 60 mph wind gusts with a lot of minor tree damage, including small branches and leaves down. Time estimated from radar.

Thunderstorm Wind in LUCAS, IOWA
From 20-JUL-19 17:15:00 to 20-JUL-19 17:15:00 (CST-6)
Location: CHARITON MUNI ARPT
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Chariton Municipal Airport AWOS recorded a 60 mph wind gust.

Thunderstorm Wind in MAHASKA, IOWA
From 20-JUL-19 17:55:00 to 20-JUL-19 17:55:00 (CST-6)
Location: CEDAR
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Department of Highways

Iowa DOT reported power lines down on IA 23 near the intersection of Teller Ave, blocking both lanes. They also advised there are possible sparking power lines near the roadway just east of that location. Time estimated from radar.

Thunderstorm Wind in POLK, IOWA
From 20-JUL-19 18:00:00 to 20-JUL-19 18:00:00 (CST-6)
Location: CLIVE
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Amateur Radio

Amateur radio reported a large tree down, 20 to 30 feet tall and about 6 inches in diameter. Reported location at 142nd and Lakeview, in Clive.

Thunderstorm Wind in MONROE, IOWA
From 20-JUL-19 17:54:00 to 20-JUL-19 17:54:00 (CST-6)
Location: ALBIA
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter estimated 60 mph wind gusts.

Thunderstorm Wind in WAPELLO, IOWA
From 20-JUL-19 18:00:00 to 20-JUL-19 18:00:00 (CST-6)
Location: (OTM)OTTUMWA INDSTRL
Magnitude: 53.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Ottumwa Regional Airport ASOS recorded a 61 mph wind gust.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 18:00:00 to 20-JUL-19 18:00:00 (CST-6)
Location: SHULER MINE
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: NWS Employee

NWS employee estimated 60 mph winds, including the patio partition blown down.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 18:04:00 to 20-JUL-19 18:04:00 (CST-6)
Location: SHULER MINE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported an 8 inch diameter tree branch down near Warrior Lane and Hickman.

Thunderstorm Wind in WAYNE, IOWA
From 20-JUL-19 18:10:00 to 20-JUL-19 18:10:00 (CST-6)
Location: SEYMOUR
Magnitude: 52.00 EG
Property damage: 10.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Wayne County emergency manager reported power lines down in town. Time estimated from radar.

Thunderstorm Wind in POLK, IOWA
From 20-JUL-19 18:15:00 to 20-JUL-19 18:15:00 (CST-6)
Location: SWANWOOD
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

Public reported a large tree branch, 6 to 8 inches in diameter, snapped. This is a delayed report. Time estimated from radar.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 18:05:00 to 20-JUL-19 18:05:00 (CST-6)
Location: SHULER MINE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

NWS employee reported a 4 to 5 inch diameter tree branch down on the side of Alices Road. This is a delayed report and time estimated from radar.

Thunderstorm Wind in DALLAS, IOWA
From 20-JUL-19 18:05:00 to 20-JUL-19 18:05:00 (CST-6)
Location: SHULER MINE
Magnitude: 52.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: NWS Employee

NWS employee reported power poles leaning over halfway to the ground. This is a delayed report.

Heavy Rain in WAPELLO, IOWA
From 20-JUL-19 18:00:00 to 20-JUL-19 21:00:00 (CST-6)
Location: RUTLEDGE
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported heavy rainfall of about 3 inches from Saturday storms. This is a delayed report. Beginning and ending times estimated from radar.

Thunderstorm Wind in GUTHRIE, IOWA
From 20-JUL-19 17:15:00 to 20-JUL-19 17:23:00 (CST-6)
Location: BAGLEY
Magnitude: 60.00 EG
Property damage: 10.00K
Crop damage: 50.00K
Reported by: NWS Employee

An off-duty NWS employee reported damage to two farmsteads near Yale with doors blown in on sheds and some metal blown out of the side. Tree damage near the two properties and in and around the town of Yale was also reported. Numerous branches were down in the area with a few large branches down as well. A couple full, old hollow trees were down near the properties. Corn was flattened in the area.