NWS acknowledges negative effect of turbines on weather radar  

Credit:  By Matt Surtel, The Daily News, thedailynewsonline.com 24 June 2009 ~~

SHELDON — Short of an extreme weather emergency, radar interference from Wyoming County’s wind farms isn’t expected to be much of an issue, a National Weather Service meteorologist said Monday.

Officials from the NWS released a statement last week describing the effects of wind turbines on its Buffalo-based radar.

The issue is probably most visible as “storms” usually located above the towns of Sheldon, Wethersfield and Eagle during weather reports on Buffalo and Rochester television newscasts.

“From a day-to-day perspective it’s more of an annoyance,” said meteorologist David Zaff of the Buffalo NWS station.

The false weather returns happen when beams from the radars are reflected off the rotating turbine blades. A small portion of the “return energy” is detected and shows up as precipitation.

Though designed to filter out buildings, mountains and other stationary objects, the weather radars can’t filter out the moving blades.

That could potentially be an issue if severe weather was moving through the area, since an untrained eye could have trouble telling the difference, Zaff said.

“Most of us here shouldn’t have a problem with that,” he said. “The only problem with that is if there’s a severe weather event moving through the turbines. Then we would have an issue.”

The biggest problem in Buffalo is that Wyoming County’s wind turbines are at an elevation higher than the weather radar, he said. The unit’s elevation is 790 feet above sea level and designed to look upward.

The wind farms are about 35 miles away, and the turbine blades spin at an elevation of about 2,000 feet, he said. That places them directly in the radar’s line-of-sight, creating the false returns.

The problems show up as false precipitation reports, bad wind data, and similar readings.

There’s no way to program out the turbine reflections, Zaff said, since the wind occurs at different speeds and directions. The problems don’t happen when the blades are still.

“We could put a big circle around (the wind farm areas) and say don’t do anything there, but that’s the equivalent of putting a black hole there,” he said. “We wouldn’t have any data.”

Humans can weed out most of the problems, but the NWS computers themselves will have trouble, he said. It’s actually a national issue as wind farms become more common.

The NWS is working on the issue, Zaff said. Given wind energy’s popularity, he said, he doesn’t think it’s going to go away.

He compares the false radar returns to a teenager’s pimple.

“It’s an ugly little blotch you don’t really want there,” he said. “Like a teenager you can live with it, but you don’t really want it anyway.”