From an article by Pat Sims in the Wisconsin State Journal:

Wind turbines and Doppler radar are silently dueling in the skies over Dodge County, meteorologists say.

Butler Ridge, a new energy wind farm in east-central Dodge County, is interfering with the Weather Surveillance Doppler Radar at the Sullivan office in eastern Jefferson County, said Marc Ravinsky, senior meteorologist at the National Weather Service in Sullivan.

Visual noise from the 36 wind turbines could mask or distort severe weather taking place in the same area, Ravinsky said. That could reduce the effectiveness of storm warnings in the vicinity, he said.

The Butler Ridge wind farm, which began operation in February, is in the town of Herman, about 60 miles northeast of Madison and about 30 miles directly north of the radar at the Sullivan weather service office.

“Unfortunately, the Butler Ridge wind farm and its turbines are within the radar line of sight of the NWS Doppler radar in eastern Jefferson County,” Ravinsky said.

The 400-foot wind turbine rotors and the motion of the blades reflect back a small part of the radar’s electromagnetic energy. The radar processes the echo as precipitation and plots it on the map, so the wind farm could be mistaken for a storm system, he said.

Ed Blume, spokesman for RENEW Wisconsin, a nonprofit renewable energy advocacy group based in Madison, said the conflict between radar and wind farms needs to be resolved.

“Wind energy will make up probably 90 percent of the renewable energy needed to satisfy renewable energy standards set by the state,” Blume said. “And with wind turbines, they must be located in a windy location.”