Basic Summary: A cluster of storms in northeast Nebraska and southeast South Dakota developed into the destructive derecho that raced eastward across large portions of Iowa, northern Illinois, southern Wisconsin, northern Indiana, and southern Michigan during the morning and afternoon of August 10th. The strongest winds were experienced in central and east-central Iowa where 100+ mph winds were observed. Some of the strongest winds were in an area from roughly Marshalltown, IA eastward along the Highway 30 corridor to the Mississippi River, where estimated winds exceeded 120+ mph and approached 140 mph. A number of QLCS tornadoes were also experienced within the Highway 30 corridor. One of the most remarkable aspects of the derecho was the duration of severe winds, with many areas experiencing at least periodic, if not persistent, severe level (58+ mph) winds over a roughly 30 minute time frame. As the derecho moved eastward out of Iowa, it continued to expand, but weakened from its peak strength. Winds continued to exceed severe criteria (58+ mph) in Illinois, Wisconsin, Indiana, and Michigan and began to produce additional QLCS tornadoes across northern Illinois before fading out across northern Indiana and southern Michigan.
In the wake of the derecho, damage was substantial in many areas, rural and urban. Many agriculture fields, mainly corn, were flattened within the swaths of strongest winds. Initial estimates suggest at least 850,000 acres of partial or complete crop loss occurred from this event. Within urban and wooded areas extensive tree and structure damage was seen, including complete roof failure in a few instances. At its peak, total estimated customers without power exceeded 1.4 million across the affected states. In total, early estimates on losses (agriculture, infrastructure, private property) have exceeded $7.5 billion across the states affected.
Environment: Broadly speaking, it was a ripe day for thunderstorms across the affected area with MUCAPE values often exceeding 3500-4000 J/kg by the mid morning hours concurrent with mid-upper level short wave support, and indications that any cold pool development would be strong (difference between cold pool and ambient air) and potentially long lived. For detailed environmental analysis, including soundings, please view the various local NWS office event review pages: NWS Des Moines, NWS Quad Cities, NWS Chicago, NWS Milwaukee, NWS Central Illinois, NWS Northern Indiana, or NWS Indianapolis.
Additional Details: Numerous injuries occurred during the derecho and in the aftermath during cleanup, including 4 direct and indirect deaths of which 3 occurred in Iowa (two in Poweshiek County and one in Linn County) and 1 in Indiana (Fort Wayne).
Disclaimer: The August 10, 2020 derecho resulted in widespread high-end damage across large portions of central and southern Iowa. Given the size and scope of the event and understanding that final damage and loss estimates (agriculture, infrastructure, and private property) will take months to complete, the NWS is not able to estimate the monetary impact at this time. Values may be added as more data becomes from various sources in future months.

Thunderstorm Wind in CARROLL, IOWA
From 10-AUG-20 08:36:00 to 10-AUG-20 08:36:00 (CST-6)
Location: MANNING
Magnitude: 56.00 EG
Reported by: Trained Spotter

A trained spotter reported a large tree limb 6 inches in diameter and 20 feet long was downed. Several smaller limbs were downed as well.

Thunderstorm Wind in GUTHRIE, IOWA
From 10-AUG-20 09:00:00 to 10-AUG-20 09:00:00 (CST-6)
Location: BAGLEY
Magnitude: 61.00 EG
Reported by: Emergency Manager

Emergency manager reported an outbuilding had the roof blown off. Time estimated via radar.

Thunderstorm Wind in CARROLL, IOWA
From 10-AUG-20 09:15:00 to 10-AUG-20 09:15:00 (CST-6)
Location: TEMPLETON
Magnitude: 65.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trainer spotter reported large trees down blocking roads. Wind was still blowing at time of report.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:25:00 to 10-AUG-20 09:25:00 (CST-6)
Location: PERRY
Magnitude: 70.00 EG
Reported by: Emergency Manager

Emergency manager reported a two foot diameter tree limb down in Perry.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:50:00 to 10-AUG-20 10:50:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 83.00 EG
Reported by: Emergency Manager

Emergency manager reported roof damage to a home. Time estimated.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:32:00 to 10-AUG-20 09:32:00 (CST-6)
Location: PANTHER
Magnitude: 65.00 EG
Reported by: Trained Spotter

Trained spotter reported a large tree limb hit a home, causing the home to lose power.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:32:00 to 10-AUG-20 09:32:00 (CST-6)
Location: PANTHER
Magnitude: 65.00 EG
Reported by: Trained Spotter

Trained spotter reported a large tree limb hit a home, causing the home to lose power.

Thunderstorm Wind in CALHOUN, IOWA
From 10-AUG-20 09:00:00 to 10-AUG-20 09:00:00 (CST-6)
Location: ROCKWELL CITY
Magnitude: 70.00 EG
Reported by: Trained Spotter

A trained spotter reported 8 inch tree limbs down, power lines down, and trees down all over town.

Thunderstorm Wind in BOONE, IOWA
From 10-AUG-20 09:52:00 to 10-AUG-20 09:52:00 (CST-6)
Location: ERICSON
Magnitude: 65.00 EG
Reported by: Public

A public report of a semi blown over at US highway 30 and Highway 17 interchange. Time estimated via radar.

Thunderstorm Wind in BOONE, IOWA
From 10-AUG-20 09:54:00 to 10-AUG-20 09:54:00 (CST-6)
Location: ERICSON
Magnitude: 87.00 EG
Reported by: Trained Spotter

A trained spotter reported several large tree limbs down and power out.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:10:00 to 10-AUG-20 10:10:00 (CST-6)
Location: ELKHART
Magnitude: 74.00 MG
Reported by: Mesonet

Mesonet station reported a 74 kts wind gust.

Thunderstorm Wind in STORY, IOWA
From 10-AUG-20 10:10:00 to 10-AUG-20 10:10:00 (CST-6)
Location: AMES
Magnitude: 54.00 MG
Reported by: Mesonet

Mesonet station reported a 54 knot wind gust.

Thunderstorm Wind in CALHOUN, IOWA
From 10-AUG-20 09:15:00 to 10-AUG-20 09:15:00 (CST-6)
Location: ROCKWELL CITY
Magnitude: 61.00 EG
Reported by: NWS Storm Survey

No LSRs were transmitted from within the county during the August 10 derecho event. However, it is estimated by the NWS that areas of the county experienced severe winds and associated damage based on surrounding county LSRs and other available information.

Thunderstorm Wind in STORY, IOWA
From 10-AUG-20 10:11:00 to 10-AUG-20 10:11:00 (CST-6)
Location: AMES
Magnitude: 61.00 EG
Reported by: Trained Spotter

A trained spotter reported estimated wind gusts over 70 mph.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:15:00 to 10-AUG-20 10:15:00 (CST-6)
Location: SWANWOOD
Magnitude: 68.00 MG
Reported by: AWOS

AWOS measurd a 68 knot wind gust.

Thunderstorm Wind in JASPER, IOWA
From 10-AUG-20 10:20:00 to 10-AUG-20 10:20:00 (CST-6)
Location: COLFAX
Magnitude: 70.00 EG
Reported by: Public

Public report of winds gusts between 70 to 80 mph.

Thunderstorm Wind in STORY, IOWA
From 10-AUG-20 10:24:00 to 10-AUG-20 10:24:00 (CST-6)
Location: AMES
Magnitude: 61.00 EG
Reported by: Trained Spotter

A trained spotter reported wind gust on Iowa State University campus of 65 to 75 mph with extensive tree damage and power outages.

Thunderstorm Wind in ADAIR, IOWA
From 10-AUG-20 09:40:00 to 10-AUG-20 09:40:00 (CST-6)
Location: GREENFIELD
Magnitude: 50.00 EG
Reported by: NWS Storm Survey

No LSRs were transmitted from within the county during the August 10 derecho event. However, it is estimated by the NWS that northern areas of the county experienced severe winds and associated damage based on surrounding county LSRs and other available information.

Thunderstorm Wind in CLARKE, IOWA
From 10-AUG-20 09:54:00 to 10-AUG-20 09:54:00 (CST-6)
Location: MURRAY
Magnitude: 56.00 EG
Reported by: Trained Spotter

A trained spotter reported damage to home foundation and several large trees down, plus a very large tree trunk down.

Thunderstorm Wind in CALHOUN, IOWA
From 10-AUG-20 09:55:00 to 10-AUG-20 09:55:00 (CST-6)
Location: RANDS
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotter reported trees down and roof off building.

Thunderstorm Wind in BOONE, IOWA
From 10-AUG-20 09:57:00 to 10-AUG-20 09:57:00 (CST-6)
Location: BOONE
Magnitude: 65.00 EG
Reported by: Public

Public report of trees down and power out.

Thunderstorm Wind in DECATUR, IOWA
From 10-AUG-20 10:26:00 to 10-AUG-20 10:26:00 (CST-6)
Location: (30I)LAMONI MUNI ARP
Magnitude: 54.00 MG
Reported by: ASOS

ASOS at Lamoni airport reported a 54 knot wind gust.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:30:00 to 10-AUG-20 10:30:00 (CST-6)
Location: CARNEY
Magnitude: 67.00 MG
Reported by: Public

Public report of a 77 mph peak wind gust from a Davis home weather station. Tree branches two to three inches in diameter broke and a 4 inch tree broke off at the ground.

Thunderstorm Wind in MARION, IOWA
From 10-AUG-20 10:35:00 to 10-AUG-20 10:35:00 (CST-6)
Location: KNOXVILLE ARPT
Magnitude: 62.00 MG
Reported by: AWOS

Knoxville airport AWOS reported a 62 knot wind gust.

Thunderstorm Wind in HARDIN, IOWA
From 10-AUG-20 10:38:00 to 10-AUG-20 10:38:00 (CST-6)
Location: HUBBARD
Magnitude: 67.00 MG
Reported by: Mesonet

Mesonet station reported a 67 knot wind gust.

Thunderstorm Wind in JASPER, IOWA
From 10-AUG-20 10:40:00 to 10-AUG-20 10:40:00 (CST-6)
Location: PRAIRIE CITY
Magnitude: 74.00 MG
Reported by: Mesonet

Mesonet station reported a 74 knot wind gust.

Thunderstorm Wind in HARDIN, IOWA
From 10-AUG-20 10:43:00 to 10-AUG-20 10:43:00 (CST-6)
Location: HUBBARD
Magnitude: 61.00 EG
Reported by: Emergency Manager

Emergency manager reported numerous large trees down with winds estimated at 70 mph.

Tornado in MARSHALL, IOWA
From 10-AUG-20 10:30:00 to 10-AUG-20 10:31:00 (CST-6)
Location: LA MOILLE
Tornado F-scale: EFU
Property damage: 0.00K
Crop damage: 0.50K
Reported by: Other Federal Agency

Brief QLCS tornado on leading edge of convection through agricultural fields.  Path found via high resolution satellite imagery.  The tornado impacted no damage indicators, hence the EFU rating.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:12:00 to 10-AUG-20 10:12:00 (CST-6)
Location: URBANDALE
Magnitude: 61.00 EG
Reported by: Broadcast Media

WOI TV relayed a report of trees down and damage to roofs.

Thunderstorm Wind in HAMILTON, IOWA
From 10-AUG-20 09:54:00 to 10-AUG-20 09:54:00 (CST-6)
Location: WEBSTER CITY ARPT
Magnitude: 52.00 MG
Reported by: AWOS

AWOS reported a 52 knot wind gust.

Thunderstorm Wind in MAHASKA, IOWA
From 10-AUG-20 10:57:00 to 10-AUG-20 10:57:00 (CST-6)
Location: LEIGHTON
Magnitude: 65.00 MG
Reported by: Mesonet

A mesonet station reported a wind gust of 65 knots.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:19:00 to 10-AUG-20 10:19:00 (CST-6)
Location: WEST DES MOINES
Magnitude: 61.00 EG
Reported by: Trained Spotter

Trained spotter reported a large tree down.

Thunderstorm Wind in STORY, IOWA
From 10-AUG-20 10:20:00 to 10-AUG-20 10:20:00 (CST-6)
Location: NEVADA
Magnitude: 65.00 EG
Reported by: Public

Public report of trees down with power flickering.

Thunderstorm Wind in CRAWFORD, IOWA
From 10-AUG-20 08:30:00 to 10-AUG-20 08:30:00 (CST-6)
Location: DENISON
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement reports tree damage in town and throughout the county. A tree also fell on neighbors car. Time estimated.

Thunderstorm Wind in JASPER, IOWA
From 10-AUG-20 10:24:00 to 10-AUG-20 10:24:00 (CST-6)
Location: COLFAX
Magnitude: 70.00 EG
Reported by: Trained Spotter

A trained spotter reported a large tree blocking both lanes of Highway F48 in Colfax.

Thunderstorm Wind in STORY, IOWA
From 10-AUG-20 10:34:00 to 10-AUG-20 10:34:00 (CST-6)
Location: SLATER
Magnitude: 87.00 EG
Reported by: Trained Spotter

A trained spotter reported large tree branches down, street signs blown down in town, and part of a roof blown off a home. Time estimated.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:39:00 to 10-AUG-20 10:39:00 (CST-6)
Location: GRIMES
Magnitude: 65.00 EG
Reported by: Amateur Radio

Amateur radio report of multiple tree limbs down with the largest eight inches in diameter. Time estimated.

Thunderstorm Wind in HARDIN, IOWA
From 10-AUG-20 10:47:00 to 10-AUG-20 10:47:00 (CST-6)
Location: UNION
Magnitude: 83.00 EG
Reported by: Trained Spotter

A trained spotter reported damage to barns and roofs.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:51:00 to 10-AUG-20 10:51:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 87.00 EG
Reported by: Storm Chaser

A storm chaser reported several large sections of roofs blown off buildings along old highway 30 on south side of Marshalltown.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 09:59:00 to 10-AUG-20 09:59:00 (CST-6)
Location: URBANDALE
Magnitude: 61.00 EG
Reported by: Public

Public report of tree damage at 75th and Diamond in Urbandale.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:30:00 to 10-AUG-20 10:30:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 87.00 EG
Reported by: Public

A public report of 100 to 120 cars with windows blown out at a factory. Time estimated.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:00:00 to 10-AUG-20 10:00:00 (CST-6)
Location: BONDURANT
Magnitude: 65.00 EG
Reported by: Trained Spotter

Trained spotter reported numerous trees and power lines down. Time estimated.

Thunderstorm Wind in WARREN, IOWA
From 10-AUG-20 10:03:00 to 10-AUG-20 10:03:00 (CST-6)
Location: CUMMING
Magnitude: 56.00 EG
Reported by: Trained Spotter

Trained spotter reported several large trees down throughout the town of Cumming. Time estimated by radar.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:05:00 to 10-AUG-20 10:05:00 (CST-6)
Location: URBANDALE
Magnitude: 61.00 EG
Reported by: Public

Public report via social media of roof damage to Buccaneer Arena at 72nd and Hickman Rd. Time estimated.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:05:00 to 10-AUG-20 10:05:00 (CST-6)
Location: SAYDELL
Magnitude: 61.00 EG
Reported by: Trained Spotter

Trained spotter reported twelve to eight inch diameter trees down.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:10:00 to 10-AUG-20 10:10:00 (CST-6)
Location: ALTOONA
Magnitude: 56.00 EG
Reported by: Trained Spotter

A trained spotter reported branches down.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:26:00 to 10-AUG-20 10:26:00 (CST-6)
Location: ORALABOR
Magnitude: 70.00 EG
Reported by: Public

Public report of mailboxes, trees, and limbs of undetermined size down.

Thunderstorm Wind in HARDIN, IOWA
From 10-AUG-20 10:52:00 to 10-AUG-20 10:52:00 (CST-6)
Location: GIFFORD
Magnitude: 74.00 EG
Reported by: Public

Public report via social media of numerous trees and power lines downed.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 11:00:00 to 10-AUG-20 11:00:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 87.00 EG
Reported by: Public

Public report of significant structural and tree damage. Time estimated.

Thunderstorm Wind in POWESHIEK, IOWA
From 10-AUG-20 11:10:00 to 10-AUG-20 11:10:00 (CST-6)
Location: GRINNELL ARPT
Magnitude: 74.00 EG
Reported by: Trained Spotter

A trained spotter reported a semi blown over on Interstate 80 just west of the Grinnell interchange.

Thunderstorm Wind in GRUNDY, IOWA
From 10-AUG-20 11:15:00 to 10-AUG-20 11:15:00 (CST-6)
Location: REINBECK
Magnitude: 61.00 EG
Reported by: Trained Spotter

A trained spotter reported trees down across roads all over town. Time estimated.

Thunderstorm Wind in TAMA, IOWA
From 10-AUG-20 11:30:00 to 10-AUG-20 11:30:00 (CST-6)
Location: ELBERON
Magnitude: 87.00 EG
Reported by: Public

Public report of grain bins blown in and severely damaged. Widespread crop damage across Tama county. Time estimated.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:43:00 to 10-AUG-20 10:43:00 (CST-6)
Location: LURAY
Magnitude: 79.00 MG
Reported by: Mesonet

The Marshalltown mesonet station reported a wind gust of 79 knots.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:50:00 to 10-AUG-20 10:50:00 (CST-6)
Location: MARSHALLTOWN ARPT
Magnitude: 86.00 MG
Reported by: ASOS

The ASOS at Marshalltown airport reported a gust of 86 knots with high winds still in progress.

Thunderstorm Wind in GUTHRIE, IOWA
From 10-AUG-20 09:15:00 to 10-AUG-20 09:15:00 (CST-6)
Location: GUTHRIE CENTER
Magnitude: 61.00 EG
Reported by: Trained Spotter

Trained spotter reported trees down. Wind was still blowing at time of report.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:10:00 to 10-AUG-20 10:10:00 (CST-6)
Location: DODGE FLD ARPT
Magnitude: 61.00 EG
Reported by: NWS Employee

An NWS employee reported and uprooted tree in northwest Johnston. Time estimated.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:10:00 to 10-AUG-20 10:10:00 (CST-6)
Location: ORALABOR
Magnitude: 70.00 EG
Reported by: Trained Spotter

A trained spotter reported six inch and larger tree limbs down with power outages. Severe winds lasted 30 minutes.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:13:00 to 10-AUG-20 10:13:00 (CST-6)
Location: URBANDALE
Magnitude: 61.00 EG
Reported by: Broadcast Media

WHO TV relayed a report that part of the Buccaneers Arena roof was blown off.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:14:00 to 10-AUG-20 10:14:00 (CST-6)
Location: DES MOINES
Magnitude: 56.00 EG
Reported by: Trained Spotter

A trained spotter reported large tree branches down.

Thunderstorm Wind in STORY, IOWA
From 10-AUG-20 10:15:00 to 10-AUG-20 10:15:00 (CST-6)
Location: ZEARING
Magnitude: 87.00 EG
Reported by: Trained Spotter

A trained spotter reported damage to trees and grain bins. Time estimated.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:16:00 to 10-AUG-20 10:16:00 (CST-6)
Location: CLIVE
Magnitude: 61.00 EG
Reported by: Public

Public report of a fence blown down at 128th and Douglas.

Thunderstorm Wind in WARREN, IOWA
From 10-AUG-20 10:16:00 to 10-AUG-20 10:16:00 (CST-6)
Location: CLARKSON
Magnitude: 56.00 EG
Reported by: Public

Public report via social media of lots of tree damage in Carlisle.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:51:00 to 10-AUG-20 10:51:00 (CST-6)
Location: MARSHALLTOWN
Magnitude: 83.00 EG
Reported by: Storm Chaser

A storm chaser estimated winds between 90 to 100 mph.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:52:00 to 10-AUG-20 10:52:00 (CST-6)
Location: QUARRY
Magnitude: 92.00 MG
Reported by: Mesonet

A personal weather station reported a 92 knot wind gust.

Thunderstorm Wind in TAMA, IOWA
From 10-AUG-20 10:55:00 to 10-AUG-20 10:55:00 (CST-6)
Location: TOLEDO
Magnitude: 61.00 EG
Reported by: Emergency Manager

Emergency manager reported wind gusts over 70 mph and that a tree fell on the office.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:58:00 to 10-AUG-20 10:58:00 (CST-6)
Location: LISCOMB
Magnitude: 65.00 EG
Reported by: Trained Spotter

A trained spotter reported 75 mph wind gusts.

Thunderstorm Wind in TAMA, IOWA
From 10-AUG-20 11:00:00 to 10-AUG-20 11:00:00 (CST-6)
Location: CHELSEA
Magnitude: 78.00 EG
Reported by: Trained Spotter

A trained spotter reported 90 mph wind gusts.

Thunderstorm Wind in GRUNDY, IOWA
From 10-AUG-20 11:19:00 to 10-AUG-20 11:19:00 (CST-6)
Location: GRUNDY CENTER
Magnitude: 52.00 EG
Reported by: Trained Spotter

A trained spotter reported 60 mph wind gusts with pea sized hail.

Thunderstorm Wind in WAPELLO, IOWA
From 10-AUG-20 11:35:00 to 10-AUG-20 11:35:00 (CST-6)
Location: OTTUMWA
Magnitude: 52.00 EG
Reported by: Trained Spotter

A trained spotter reported 60 mph wind gusts.

Thunderstorm Wind in POWESHIEK, IOWA
From 10-AUG-20 11:00:00 to 10-AUG-20 11:00:00 (CST-6)
Location: MALCOLM
Magnitude: 70.00 EG
Property damage: 0.00K
Reported by: Law Enforcement

Law enforcement reported a large tree fell on a home.

Thunderstorm Wind in POWESHIEK, IOWA
From 10-AUG-20 11:10:00 to 10-AUG-20 11:10:00 (CST-6)
Location: BROOKLYN
Magnitude: 70.00 EG
Reported by: Law Enforcement

Law enforcement reported damage to power lines in the area.

Thunderstorm Wind in CRAWFORD, IOWA
From 10-AUG-20 08:45:00 to 10-AUG-20 08:45:00 (CST-6)
Location: BUCK GROVE
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement reported tree damage occurred all across town.

Thunderstorm Wind in WEBSTER, IOWA
From 10-AUG-20 10:02:00 to 10-AUG-20 10:02:00 (CST-6)
Location: FT DODGE
Magnitude: 52.00 EG
Reported by: Emergency Manager

Emergency manager reported numerous trees down along with power outages.

Thunderstorm Wind in JASPER, IOWA
From 10-AUG-20 10:29:00 to 10-AUG-20 10:29:00 (CST-6)
Location: NEWTON
Magnitude: 70.00 EG
Reported by: Trained Spotter

A trained spotter reported damage throughout town with trees down and roads blocked. Time estimated.

Thunderstorm Wind in TAMA, IOWA
From 10-AUG-20 11:30:00 to 10-AUG-20 11:30:00 (CST-6)
Location: ELBERON
Magnitude: 87.00 EG
Reported by: Public

Public report of grain bins blown in and severely damaged. Widespread crop damage across Tama county. Time estimated.

Thunderstorm Wind in MARSHALL, IOWA
From 10-AUG-20 10:58:00 to 10-AUG-20 10:58:00 (CST-6)
Location: STATE CENTER
Magnitude: 74.00 EG
Reported by: Emergency Manager

Emergency manager reported significant damage in State Center with numerous cars blown off US 30 and flipped.

Thunderstorm Wind in TAMA, IOWA
From 10-AUG-20 11:01:00 to 10-AUG-20 11:01:00 (CST-6)
Location: TOLEDO
Magnitude: 87.00 EG
Reported by: COOP Observer

A coop observer reported a 60 by 90 foot machine shed completely demolished. Neighbors empty grain bins were blown across highway 63. Several large trees are snapped or uprooted. A 78 mph wind gust was reported before the weather station gave out.

Thunderstorm Wind in CARROLL, IOWA
From 10-AUG-20 09:02:00 to 10-AUG-20 09:02:00 (CST-6)
Location: CARROLL NEU ARPT
Magnitude: 64.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

AWOS reported a gust of 64 knots.

Thunderstorm Wind in CASS, IOWA
From 10-AUG-20 09:10:00 to 10-AUG-20 09:10:00 (CST-6)
Location: FLETCHER CHAPEL
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public report of 60 mph wind gust.

Thunderstorm Wind in GUTHRIE, IOWA
From 10-AUG-20 09:14:00 to 10-AUG-20 09:14:00 (CST-6)
Location: MONTEITH
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Mesonet reported a 56 knot wind gust.

Thunderstorm Wind in GREENE, IOWA
From 10-AUG-20 09:20:00 to 10-AUG-20 09:20:00 (CST-6)
Location: JEFFERSON MUNI ARPT
Magnitude: 72.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A personal weather station reported a 72 knot wind gust. Time estimated via radar.

Thunderstorm Wind in GREENE, IOWA
From 10-AUG-20 09:20:00 to 10-AUG-20 09:20:00 (CST-6)
Location: JEFFERSON MUNI ARPT
Magnitude: 72.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A personal weather station reported a 72 knot wind gust. Time estimated via radar.

Thunderstorm Wind in GUTHRIE, IOWA
From 10-AUG-20 09:21:00 to 10-AUG-20 09:21:00 (CST-6)
Location: YALE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager reported 65 mph wind gusts with pea sized hail and heavy rainfall.

Thunderstorm Wind in GUTHRIE, IOWA
From 10-AUG-20 09:21:00 to 10-AUG-20 09:21:00 (CST-6)
Location: YALE
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Emergency manager reported 65 mph wind gusts with pea sized hail and heavy rainfall.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:26:00 to 10-AUG-20 09:26:00 (CST-6)
Location: PERRY
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Public report of 70 mph winds with branches down and power out.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:33:00 to 10-AUG-20 09:33:00 (CST-6)
Location: MINBURN
Magnitude: 61.00 EG
Reported by: Fire Department/Rescue

Fire department estimated 60 to 70 mph wind gusts.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:37:00 to 10-AUG-20 09:37:00 (CST-6)
Location: ADEL
Magnitude: 56.00 EG
Reported by: Public

Public estimate of winds over 60 mph with power flickering.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:37:00 to 10-AUG-20 09:37:00 (CST-6)
Location: ADEL
Magnitude: 56.00 EG
Reported by: Public

Public estimate of winds over 60 mph with power flickering.

Thunderstorm Wind in GREENE, IOWA
From 10-AUG-20 09:30:00 to 10-AUG-20 09:30:00 (CST-6)
Location: CHURDAN
Magnitude: 61.00 EG
Reported by: Trained Spotter

A trained spotter reported 70 mph wind gusts with debris on roads.

Thunderstorm Wind in AUDUBON, IOWA
From 10-AUG-20 08:55:00 to 10-AUG-20 08:55:00 (CST-6)
Location: AUDUBON
Magnitude: 56.00 EG
Reported by: NWS Storm Survey

No LSRs were transmitted from within the county during the August 10 derecho event. However, it is estimated by the NWS that areas of the county experienced severe winds and associated damage based on surrounding county LSRs and other available information.

Tornado in MARSHALL, IOWA
From 10-AUG-20 10:36:00 to 10-AUG-20 10:37:00 (CST-6)
Location: MINERVA
Tornado F-scale: EFU
Property damage: 0.00K
Crop damage: 0.50K
Reported by: Other Federal Agency

Brief tornado captured from post event UAS survey.  Stayed in cropland with no impacts to damage indicators, hence the EFU rating.

Tornado in MARSHALL, IOWA
From 10-AUG-20 10:39:00 to 10-AUG-20 10:42:00 (CST-6)
Location: MARIETTA
Tornado F-scale: EF1
Property damage: 20.00K
Crop damage: 1.50K
Reported by: Other Federal Agency

Tornado initially found from high resolution satellite imagery and confirmed via UAS overflight.  Damage was done to crop and trees.  Some minor damage to housing structures as well, but mostly superficial.

Tornado in TAMA, IOWA
From 10-AUG-20 11:01:00 to 10-AUG-20 11:02:00 (CST-6)
Location: GLADBROOK
Tornado F-scale: EFU
Property damage: 0.00K
Crop damage: 1.00K
Reported by: Other Federal Agency

Tornado associated with QLCS derecho first observed via high resolution satellite imagery.  Path was also overflown by UAS confirming convegent path of debris.  No damage indicators were impacted, hence the EFU designation.

Hail in SAC, IOWA
From 10-AUG-20 08:58:00 to 10-AUG-20 08:58:00 (CST-6)
Location: AUBURN
Magnitude: 1.50 
Reported by: Other Federal Agency

Wind-driven hail caused significant damage northeast of Breda. Winds Estimated to be 60 mph or greater. Delayed Report. Time estimated by radar.

Thunderstorm Wind in CRAWFORD, IOWA
From 10-AUG-20 08:30:00 to 10-AUG-20 08:30:00 (CST-6)
Location: KIRON
Magnitude: 52.00 EG
Reported by: Law Enforcement

Law enforcement reported a semi jackknifed due to strong winds.

Thunderstorm Wind in CRAWFORD, IOWA
From 10-AUG-20 08:45:00 to 10-AUG-20 08:45:00 (CST-6)
Location: BUCK GROVE
Magnitude: 56.00 EG
Reported by: Law Enforcement

Law enforcement reported tree damage occurred all across town.

Thunderstorm Wind in BOONE, IOWA
From 10-AUG-20 09:38:00 to 10-AUG-20 09:38:00 (CST-6)
Location: WOLF
Magnitude: 56.00 EG
Reported by: Trained Spotter

A trained spotter reported winds over 60 mph with tree damage. Time estimated.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:40:00 to 10-AUG-20 09:40:00 (CST-6)
Location: DE SOTO
Magnitude: 61.00 EG
Reported by: Trained Spotter

A trained spotter reported 70 mph winds with lots of small trees down and several anchored swing sets toppled over.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 09:47:00 to 10-AUG-20 09:47:00 (CST-6)
Location: ASHAWA
Magnitude: 61.00 EG
Reported by: Trained Spotter

A trained spotter reported 70 mph gusts at Mills Civic Parkway and Interstate 35.

Thunderstorm Wind in DALLAS, IOWA
From 10-AUG-20 09:48:00 to 10-AUG-20 09:48:00 (CST-6)
Location: ADEL
Magnitude: 61.00 MG
Reported by: Trained Spotter

A trained spotter reported 70 mph gusts in the City of Adel with limbs down and objects blown around.

Thunderstorm Wind in MADISON, IOWA
From 10-AUG-20 09:55:00 to 10-AUG-20 09:55:00 (CST-6)
Location: BEVINGTON
Magnitude: 65.00 EG
Reported by: Trained Spotter

A trained spotter reported a 75 mph wind gust.

Thunderstorm Wind in MADISON, IOWA
From 10-AUG-20 09:55:00 to 10-AUG-20 09:55:00 (CST-6)
Location: BEVINGTON
Magnitude: 65.00 EG
Reported by: Trained Spotter

A trained spotter reported a 75 mph wind gust.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:00:00 to 10-AUG-20 10:00:00 (CST-6)
Location: (DSM)DES MOINES INTL
Magnitude: 70.00 EG
Reported by: Trained Spotter

A trained spotter reported 80 mph wind gusts with several large tree limbs down and tree trunks snapped. Roads were blocked.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:01:00 to 10-AUG-20 10:01:00 (CST-6)
Location: ELKHART
Magnitude: 60.00 MG
Reported by: Mesonet

Mesonet station reported a 60 knot wind gust.

Thunderstorm Wind in WARREN, IOWA
From 10-AUG-20 10:03:00 to 10-AUG-20 10:03:00 (CST-6)
Location: INDIANOLA
Magnitude: 50.00 MG
Reported by: Public

Public report of 60 mph wind gust.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:04:00 to 10-AUG-20 10:04:00 (CST-6)
Location: (DSM)DES MOINES INTL
Magnitude: 65.00 MG
Reported by: ASOS

Des Moines Airport ASOS reported a wind gust of 65 knots.

Thunderstorm Wind in BOONE, IOWA
From 10-AUG-20 10:06:00 to 10-AUG-20 10:06:00 (CST-6)
Location: MADRID
Magnitude: 51.00 MG
Reported by: Mesonet

Mesonet station reported a 51 knot wind gust.

Thunderstorm Wind in POLK, IOWA
From 10-AUG-20 10:06:00 to 10-AUG-20 10:06:00 (CST-6)
Location: CLOVER HILLS
Magnitude: 61.00 EG
Reported by: NWS Employee

NWS employee reported 70 mph wind gusts and lots of small branches down.

Thunderstorm Wind in STORY, IOWA
From 10-AUG-20 10:07:00 to 10-AUG-20 10:07:00 (CST-6)
Location: GILBERT
Magnitude: 61.00 EG
Reported by: Trained Spotter

A trained spotter reported 70 mph wind gusts.

Thunderstorm Wind in SAC, IOWA
From 10-AUG-20 08:45:00 to 10-AUG-20 08:45:00 (CST-6)
Location: SAC CITY
Magnitude: 61.00 EG
Reported by: NWS Storm Survey

No LSRs were transmitted from within the county during the August 10 derecho event. However, it is estimated by the NWS that areas of the county experienced severe winds and associated damage based on surrounding county LSRs and other available information.