Multiple rounds of strong to severe thunderstorms moved across southern WI as a warm front slowly moved north through the region. Flash flooding occurred in Washington, Ozaukee, and northern Milwaukee Counties which was followed by prolonged river flooding. Four to eight inches of rain had fallen over this area. The thunderstorms produced sporadic tree and power line damage across southern WI.

Flash Flood in MILWAUKEE, WISCONSIN
From 26-AUG-18 22:25:00 to 27-AUG-18 01:00:00 (CST-6)
Location: MILWAUKEE HOAN BRIDGE
Flood cause: Heavy Rain
Property damage: 25.00K
Crop damage: 0.00K
Reported by: Broadcast Media

Flash flooding of some streets in northern Milwaukee County. This included stalled vehicles in flooded intersections of Teutonia Ave. and Capitol Dr. and the intersection of 20th St. and Capitol Dr. Two to four inches of rain had fallen over the area.

Flash Flood in OZAUKEE, WISCONSIN
From 26-AUG-18 22:45:00 to 27-AUG-18 04:00:00 (CST-6)
Location: BAYSIDE
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash flooding of streets in areas of Mequon including the intersection of Cedarburg Rd. and Division St. Additional flash flooding of streets in Grafton and other urban areas of southern Ozaukee County.

Flash Flood in OZAUKEE, WISCONSIN
From 27-AUG-18 01:30:00 to 27-AUG-18 04:00:00 (CST-6)
Location: FIVE CORNERS
Flood cause: Heavy Rain
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash flooding of streets in Saukville, Port Washington, Grafton, and other urban and rural areas of southern Ozaukee County.

Flash Flood in WASHINGTON, WISCONSIN
From 27-AUG-18 01:30:00 to 27-AUG-18 04:00:00 (CST-6)
Location: HOLY HILL
Flood cause: Heavy Rain
Property damage: 584.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Flash flooding of city streets in Jackson and West Bend and other urban areas of Washington County. Up to 18 inches of water depth on some streets in West Bend. Flooding of creeks and lowland in rural areas with various roads flooded or washed out. The Town of Farmington experienced the greatest impact from the flooding. Overall, 24 homes had affected flood damage with 5 homes experiencing minor flood damage.

Thunderstorm Wind in SAUK, WISCONSIN
From 26-AUG-18 14:45:00 to 26-AUG-18 14:45:00 (CST-6)
Location: NORTH FREEDOM
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Law Enforcement

At least six different locations of trees or large branches down on roads.

Flood in WASHINGTON, WISCONSIN
From 27-AUG-18 04:00:00 to 27-AUG-18 19:00:00 (CST-6)
Location: HOLY HILL
Flood cause: Heavy Rain
Property damage: 1.00K
Crop damage: 5.00K
Reported by: Emergency Manager

Flooding of lowland and various creeks and rivers continued, including road closures and washouts. The Town of Farmington was impacted the greatest by the flooding.

Thunderstorm Wind in COLUMBIA, WISCONSIN
From 26-AUG-18 15:15:00 to 26-AUG-18 15:15:00 (CST-6)
Location: PORTAGE
Magnitude: 50.00 EG
Property damage: 3.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Several trees and power lines down.

Lightning in COLUMBIA, WISCONSIN
From 26-AUG-18 15:18:00 to 26-AUG-18 15:18:00 (CST-6)
Location: LODI
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A few trees and a powerline down due to a lightning strike.

Thunderstorm Wind in WASHINGTON, WISCONSIN
From 26-AUG-18 17:10:00 to 26-AUG-18 17:13:00 (CST-6)
Location: JACKSON
Magnitude: 61.00 EG
Property damage: 5.00K
Crop damage: 0.00K
Reported by: NWS Storm Survey

Tree damage concentrated in the Jackson area including one large uprooted tree. A parking sign with a concrete base was tipped over.

Flood in OZAUKEE, WISCONSIN
From 27-AUG-18 04:00:00 to 27-AUG-18 19:00:00 (CST-6)
Location: BAYSIDE
Flood cause: Heavy Rain
Property damage: 854.00K
Crop damage: 5.00K
Reported by: Law Enforcement

Overall, many flooded roads and lowlands due to 4 to 8 inches of rain. Some road washouts and homes flooded. I-43 was closed through late morning due to flooding between mile marker 101 and 107. Many of the cities in the county experienced severe street flooding and closures. The Milwaukee River reached minor flood stage throughout the county with many roads and intersections flooded and closed near the river, especially near Saukville and Cedarburg. Some piers washed away on the Milwaukee River. Dozens of vehicles across the county were stranded in flood waters. Overall, 76 homes sustained affected flood damage, 52 homes with minor flood damage, and 11 homes with major damage. 25 businesses sustained minor flood damage and 5 businesses sustained major flood damage.

Thunderstorm Wind in JEFFERSON, WISCONSIN
From 26-AUG-18 20:18:00 to 26-AUG-18 20:18:00 (CST-6)
Location: JEFFERSON
Magnitude: 61.00 EG
Property damage: 6.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Numerous trees and branches down in Jefferson.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 26-AUG-18 20:36:00 to 26-AUG-18 20:36:00 (CST-6)
Location: LAC LA BELLE
Magnitude: 56.00 EG
Property damage: 4.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Several trees and branches down including two power lines on the west side of Lac La Belle.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 26-AUG-18 21:45:00 to 26-AUG-18 21:45:00 (CST-6)
Location: SUMMIT CORNERS
Magnitude: 50.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

A few trees and branches down on Dousman Road.

Thunderstorm Wind in WAUKESHA, WISCONSIN
From 26-AUG-18 21:45:00 to 26-AUG-18 21:45:00 (CST-6)
Location: OCONOMOWOC LAKE
Magnitude: 56.00 EG
Property damage: 2.00K
Crop damage: 0.00K
Reported by: Law Enforcement

Numerous trees and branches down on Valley Road.

Hail in DANE, WISCONSIN
From 26-AUG-18 15:33:00 to 26-AUG-18 15:33:00 (CST-6)
Location: MIDDLETON
Magnitude: 0.75 
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Public

Estimated wind gusts of 50 mph with 3/4 inch hail in Middleton.

Flood in OZAUKEE, WISCONSIN
From 27-AUG-18 19:00:00 to 31-AUG-18 23:59:00 (CST-6)
Location: THIENSVILLE
Flood cause: Heavy Rain
Property damage: 1.00K
Crop damage: 0.00K
Reported by: Emergency Manager

The Milwaukee River crested at minor flood stage at 12.2 feet during the early afternoon of August 29th, but continued flooding into the evening of September 3rd. Floodwaters spread into the backyards of homes in the Thiensville area. Water is over Elm St., Green Bay Rd., and N. Cedarburg Rd., and into Thiensville Village Park. Water is near some homes along Island Drive and Shoreland Parkway in the Mequon area. There is general lowland flooding in the Cedarburg and Thiensville areas.