Two rounds of thunderstorms impacted Southeastern Michigan on August 11: the first during the afternoon and the second during the late evening into the following morning. The first round produced widespread severe wind gusts across the area between 3 and 5pm as a well-organized line swept eastward across the state. This line knocked out power for hundreds of thousands of customers as widespread tree and power line damage occurred. A wind gust of 75 mph was measured in Mt. Clemens. A lull in activity followed for much of the evening before the next round of storms tracked eastward across the region after 10pm. Severe reports were more isolated with this round, but abundant moisture moved in and led to repeated rounds of training thunderstorms that resulted in prolonged heavy rain and flooding overnight.  Flash flooding occurred over Livingston and Macomb Counties where some areas saw 3 to 5 inches of rain. Additional severe storms occurred the early morning of the 12th along and south of the I-94 corridor before storms finally moved out. According to DTE and Consumers Energy outage reports, nearly 850,000 customers across the state lost power due to the storms.

Thunderstorm Wind in WASHTENAW, MICHIGAN
From 12-AUG-21 06:13:00 to 12-AUG-21 06:13:00 (EST-5)
Location: ANN ARBOR
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous small trees and branches reported down in the Ann Arbor area.

Thunderstorm Wind in WAYNE, MICHIGAN
From 12-AUG-21 06:24:00 to 12-AUG-21 06:24:00 (EST-5)
Location: ROMULUS
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Six inch diameter tree limbs reported down.

Thunderstorm Wind in WASHTENAW, MICHIGAN
From 12-AUG-21 06:00:00 to 12-AUG-21 06:00:00 (EST-5)
Location: PITTSFIELD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

A large tree was reported down.

Thunderstorm Wind in WAYNE, MICHIGAN
From 12-AUG-21 06:15:00 to 12-AUG-21 06:15:00 (EST-5)
Location: SHELDON
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A 8 inch diameter tree limb reported down.

Thunderstorm Wind in LENAWEE, MICHIGAN
From 12-AUG-21 05:37:00 to 12-AUG-21 05:37:00 (EST-5)
Location: CAMBRIDGE JCT
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several trailers turned over and numerous trees down at Jupiter Campground near Michigan International Speedway.

Thunderstorm Wind in MONROE, MICHIGAN
From 11-AUG-21 14:25:00 to 11-AUG-21 14:25:00 (EST-5)
Location: SCOFIELD
Magnitude: 56.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Many trees reported down, blocking road.

Thunderstorm Wind in WAYNE, MICHIGAN
From 11-AUG-21 14:44:00 to 11-AUG-21 14:44:00 (EST-5)
Location: (DTW)DETROIT METRO A
Magnitude: 55.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Flash Flood in MACOMB, MICHIGAN
From 12-AUG-21 06:00:00 to 12-AUG-21 08:00:00 (EST-5)
Location: CADY
Flood cause: Heavy Rain
Property damage: 100.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Flooded roadways were reported, especially around 13 Mile Road and Groesbeck Highway. Cars were stranded due to the flood waters.

Flash Flood in LIVINGSTON, MICHIGAN
From 12-AUG-21 03:30:00 to 12-AUG-21 05:30:00 (EST-5)
Location: FOWLERVILLE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Eastbound I-96 after Pinckney Road was closed due to flooding.

Thunderstorm Wind in LIVINGSTON, MICHIGAN
From 11-AUG-21 14:12:00 to 11-AUG-21 14:12:00 (EST-5)
Location: CHILSON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A large tree fell onto the road.

Thunderstorm Wind in LENAWEE, MICHIGAN
From 12-AUG-21 05:37:00 to 12-AUG-21 05:37:00 (EST-5)
Location: MONITOU BEACH
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Multiple large trees snapped around Devils Lake.

Thunderstorm Wind in LENAWEE, MICHIGAN
From 11-AUG-21 14:01:00 to 11-AUG-21 14:01:00 (EST-5)
Location: MACON
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Large trees, over 1 foot in diameter, were reported down. A trained spotter estimated the winds at 70 mph.

Thunderstorm Wind in LIVINGSTON, MICHIGAN
From 11-AUG-21 14:08:00 to 11-AUG-21 14:08:00 (EST-5)
Location: HAMBURG
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Multiple trees and power lines reported down.

Thunderstorm Wind in WASHTENAW, MICHIGAN
From 11-AUG-21 14:08:00 to 11-AUG-21 14:08:00 (EST-5)
Location: YORK
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous large trees uprooted and downed power lines.

Thunderstorm Wind in WASHTENAW, MICHIGAN
From 11-AUG-21 14:13:00 to 11-AUG-21 14:13:00 (EST-5)
Location: (ARB)ANN ARBOR MUNI
Magnitude: 50.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in LIVINGSTON, MICHIGAN
From 11-AUG-21 14:15:00 to 11-AUG-21 14:15:00 (EST-5)
Location: HARTLAND
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous trees reported down near Hartland.

Thunderstorm Wind in MONROE, MICHIGAN
From 11-AUG-21 14:17:00 to 11-AUG-21 14:17:00 (EST-5)
Location: LULU
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Numerous trees and power lines reported down.

Thunderstorm Wind in MONROE, MICHIGAN
From 11-AUG-21 14:21:00 to 11-AUG-21 14:21:00 (EST-5)
Location: IDA
Magnitude: 61.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Emergency Manager

Over 40 trees reported down.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:17:00 to 11-AUG-21 14:17:00 (EST-5)
Location: MILFORD
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

A large tree was blown down on Milford road.

Thunderstorm Wind in WAYNE, MICHIGAN
From 11-AUG-21 14:23:00 to 11-AUG-21 14:23:00 (EST-5)
Location: (YIP)WILOW RUN APT D
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: ASOS

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:30:00 to 11-AUG-21 14:30:00 (EST-5)
Location: CLAWSON
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Three AC rooftop units at a shopping mall center were blown over.

Thunderstorm Wind in GENESEE, MICHIGAN
From 11-AUG-21 14:27:00 to 11-AUG-21 14:27:00 (EST-5)
Location: LINDEN
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: NWS Employee

Numerous trees reported down.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:30:00 to 11-AUG-21 14:30:00 (EST-5)
Location: HIGHLAND
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Multiple trees and wires reported down in Highland Township.

Thunderstorm Wind in MONROE, MICHIGAN
From 11-AUG-21 14:30:00 to 11-AUG-21 14:30:00 (EST-5)
Location: MONROE
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A few large trees uprooted with large tree limbs down.

Thunderstorm Wind in WAYNE, MICHIGAN
From 11-AUG-21 14:30:00 to 11-AUG-21 14:30:00 (EST-5)
Location: NEW BOSTON
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Large tree fell onto power line.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:30:00 to 11-AUG-21 14:30:00 (EST-5)
Location: HOLLY
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several 10-12 inch diameter tree limbs reported down.

Thunderstorm Wind in GENESEE, MICHIGAN
From 11-AUG-21 14:39:00 to 11-AUG-21 14:39:00 (EST-5)
Location: BELSAY
Magnitude: 56.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: 911 Call Center

Dozens of trees and power lines reported down.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:42:00 to 11-AUG-21 14:42:00 (EST-5)
Location: ORTONVILLE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: County Official

A county official estimated a 60 mph wind gust.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:43:00 to 11-AUG-21 14:43:00 (EST-5)
Location: BERKLEY
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Several trees and power lines reported down near Berkley.

Thunderstorm Wind in WAYNE, MICHIGAN
From 11-AUG-21 14:43:00 to 11-AUG-21 14:43:00 (EST-5)
Location: WYANDOTTE
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

A large tree fell onto the road.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:44:00 to 11-AUG-21 14:44:00 (EST-5)
Location: AUBURN HGTS
Magnitude: 52.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A large tree was blown down.

Thunderstorm Wind in OAKLAND, MICHIGAN
From 11-AUG-21 14:53:00 to 11-AUG-21 14:53:00 (EST-5)
Location: OXFORD
Magnitude: 52.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Mesonet

Thunderstorm Wind in MACOMB, MICHIGAN
From 11-AUG-21 15:00:00 to 11-AUG-21 15:00:00 (EST-5)
Location: (MTC)MT CLEMENS/SELF
Magnitude: 65.00 MG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: AWOS

Thunderstorm Wind in GENESEE, MICHIGAN
From 11-AUG-21 21:48:00 to 11-AUG-21 21:48:00 (EST-5)
Location: FLUSHING
Magnitude: 55.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Multiple trees uprooted with large tree limbs down.

Thunderstorm Wind in WASHTENAW, MICHIGAN
From 12-AUG-21 05:47:00 to 12-AUG-21 05:47:00 (EST-5)
Location: MANCHESTER
Magnitude: 50.00 EG
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Public

Power lines reported down over the roadway.