There was a plan to prevent flooding at an I-43 construction site. Mother Nature had other ideas.
Emergency crews rescued a man from a car on a flooded I-43 Mike De Sisti, Milwaukee Journal Sentinel
There was a plan to prevent flooding around a freeway construction project along I-43. It just came 24 hours too late.
Work was scheduled to close I-43 at Good Hope Road overnight Friday into Saturday to install a larger storm sewer. Mother Nature had other plans, dumping buckets of rain on the area Friday morning that caused two complete freeway shutdowns, including at the heart of the morning commute.
What caused all this rain — ranging from 3 to 8 inches around southern Wisconsin — in such a short period of time? A very slow-moving system, National Weather Service meteorologist J.J. Wood said.
"It kept regenerating and staying over the area, moving really slowly," Wood said. "And when that happens — continuous rain over the same area, moving really slowly — the rainfall rate can get very high, causing heavy rain ... and then you get the flooding."
Flooding originally closed both north and southbound lanes on I-43 about 7 a.m., just south of Good Hope Road, where construction at Green Tree and Good Hope roads has narrowed the lanes in recent months.
By 7:20 a.m., around 3 inches of rain had rapidly drenched the area, according to the weather service.
Northbound lanes on I-43 had reopened on the interstate by 9:15 a.m. and southbound lanes were reopened a short time later — only for both to be shut down again from 11 a.m. until about noon.
Earlier in the morning, several motorists could be seen sitting on top of their cars to escape the high waters on I-43 when the flooding began.
The North Shore Fire Department assisted stranded motorists in the area. No injuries were reported.
The flooding could have been caused by a variety of reasons, said Michael Pyritz, spokesman for the northeastern region of the state Department of Transportation.
In July 2010, the same area on I-43 flooded while major construction work was being done on the Green Tree Road bridge, as storm drains on the freeway were blocked to keep construction debris out.
In addition, Pyritz said, the area is much lower than surrounding areas, easily causing water buildup. That's why the DOT had sought a new, larger storm sewer.
"I don't know what exactly occurred," Pyritz said. "There's just no definitive answer. It seemed to be a combination of elements."
Flooding on I-43 was only part of the havoc drivers across southern Wisconsin faced.
Jefferson County took the brunt of the storm, with 8.6 inches reported in parts of the county by 2:30 p.m. Friday, the weather service reports.
A man is rescued by the Watertown Fire Department after he drove his car around a barricade and float into a flooded street in Watertown. Tim Halbach, National Weather Service
The Jefferson County Sherrif's Office reported heavy flooding and had advised staying away from the northern regions of the county — Watertown and Ixonia especially — for the day.
The weather service issued flood warnings in Jefferson and Dodge counties that will remain in effect until 12:15 p.m. Saturday.
After Friday night, Wood said, the weather should quiet down across southern Wisconsin.