Wind farms can mislead weather radar, analysts find

? Wind farms have been blamed for disrupting the lives of birds, bats and, most recently, the land-bound sage grouse.

Now the weather forecaster?

The massive spinning blades affixed to towers 200 feet high can appear on Doppler radar like a violent storm or even a tornado.

The phenomenon has affected several National Weather Service radar sites in different parts the country, even leading to a false tornado alert near Dodge City, Kan. In Des Moines, Iowa, the weather service received a warning from an emergency worker who had access to Doppler radar images.

The alert was quickly called off in Kansas and meteorologists calmed the emergency worker down, but with enough wind turbines going up last year to power more than 6 million homes and a major push toward alternative energy, more false alerts seem inevitable.

New installations are concentrated in windy states like Texas, Oklahoma, Kansas, Colorado and Iowa, all part of Tornado Alley.

Dave Zaff, science and operations officer with the National Weather Service office in Buffalo, N.Y., describes the wind farms 20 to 35 miles to the southeast as “more of a pimple or a blotch on your face” that 99 percent of the time will not pose a problem.

In a worst-case scenario, a forecaster could disregard a real storm for turbine interference, but, more likely, would err on the side of caution, Zaff said.

Problems began to surface about three years ago, and seem to occur where a wind farm is built within about 11 miles of a Doppler site, said Tim Crum, with the weather service’s radar operations center in Norman, Okla.

Software can easily filter out buildings, cell towers and mountain ridges on radar screens.

Yet because weather radar seeks motion to warn of storms, there’s no way to filter out the spinning blades.

In Kansas, a computer program picked up on the pattern and issued the alert. A meteorologist aware of the phenomenon quickly called off the alert.