Wind turbines make weather forecasting more difficult
SIOUX FALLS, S.D. (AP) — 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, Kansas, in the heart of Tornado Alley.
In Des Moines, Iowa, the weather service received a frantic 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, understandably in windy states like Texas, Oklahoma, Kansas, Colorado and Iowa, all part of Tornado Alley.
Texas, which has more tornadoes than any other state, also has the most wind power capacity. 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.
But what about those busy, high-stress periods when a meteorologist is tasked with making quick decisions as storms grow violent? In a worse-case scenario, a forecaster could disregard a real storm for turbine interference, but, more likely, would err on the side of caution, Zaff said.
“If you take a glance and then all of the sudden you see red, you might issue an incorrect warning as a result,” he 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.
That could become a bigger problem because the same terrain is attractive for both weather radar and wind farms.
“They want to be out in relatively exposed areas, high terrain, those sorts of things,” Crum said. “So we sometimes are looking for the same ground, although we’re already there.”
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.
Microwave radio signals are beamed toward a particular point and meteorologists listen for the “reflection.” Experts can pick out the shape of a storm, or a tornado.
The splatter of green, yellow, orange and red on Doppler screens that are caused by wind farms can look very much like a tornado or a storm.
In Kansas, it was a computer program that picked up on the pattern and issued the alert. A meteorologist who was aware of the phenomenon quickly called off the alert.
The weather service is trying to improve its technology so that meteorologists during severe weather events can more easily tell the difference between dangerous storms and wind farms.
But there are now discussions about shutting down the wind farms when bad storms roll in.
The weather service has no say in where wind farms are sited, though it has analyzed some 500 proposed wind projects in an attempt to cut down on false alarms through better siting and layouts, said Crum.
It is also meeting regularly with AWEA, the wind power trade group.
Laurie Jodziewicz, AWEA’s manager of siting policy, said the association is making sure its members understand the emerging issue and that they consider their projects’ potential effects sooner rather than later.
“You can move turbines around as you’re planning, but once they’re in the ground they’re really, really difficult to move,” Jodziewicz said.
Aug 31, 2009 at 8:50 a.m.
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It would be interesting to see the radar cross section (RCS) data of a tornado or high speed winds vs that of a wind turbine. It would be safe to assume that straight winds are easy to distinguish vs wind turbines due to doppler in only one direction instead of two. Cyclonic activity more closely reassembles a turbine; leading and trailing edges.
Aug 31, 2009 at 8:43 a.m.
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I think there is a slight indication by virtue of the title that makes people read more into the article than really exists. The title could have had a softer entry and eliminated that reference to other claims against wind farms. The title could have read that x and the AWEA are working together to eliminate potential wind turbine interference. Something that draws out the positive as opposed to the negative.
Aug 30, 2009 at 11:24 p.m.
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alwaysoutoftowner - yes, the WSR-88D radar takes many vertical slices through the atmosphere, however, the most important slices when potentially issuing a tornado warning are the lowest 2 slices where the best indication of a low-level mesocyclone would be. Most of the time there will be a noticeable deep mesocyclone before tornadogenesis occurs, but if a storm is to interact with a boundary such as the lake breeze, warm front, outflow boundary, etc; tornadogenesis can occur without a deep persistent mesocylone preceding it. In a time when the NWS is working diligently to increase warning times, in very rare instances, wind farms can affect that. The story makes this out to be a bigger deal than it is as the interference will likely be mitigated relatively shortly with new software.
Aug 30, 2009 at 6:16 p.m.
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The National Weather Service can work around these easily. Radars, when in severe weather mode, look at the atmosphere in many horizontal slices. Wind farms show up only on the bottom slice and in very rare cases, the next slice up. Severe thunderstorms on radar show their severe nature on most of the elevated slices. Now, the radar itself has automated alerts and they can be fooled by the wind farm. But, these false alerts happen all the time for many reasons beyond wind farms. The meteorologists job is to determine which is real and which is false. It is the novices on the web who see these alerts and freak out thinking they are real. This gets lots of people excited and the media follows it up with hyped stories like this. Again, the NWS can work around this problem.
Aug 30, 2009 at 4:13 p.m.
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Runnoft,
I did not say cospiracy. Just saying if wind energy will be a source of energy for the future, dopplar radars and weather forcasters will have to improve their skills to figure out a wind turbine from a tornado. Jmo
Aug 30, 2009 at 10:05 a.m.
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There's no conspiracy to stop wind farms, and the National Weather Service is not against using them. The article does nothing more than state that wind farms do create some interference with doppler radar. Improving the radar is not the answer, however, I understand they are working on an algorithm which will be implemented into the software which "decodes" the radar data to help filter out wind farms.
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im_azkid - its not a problem in California because they don't have the frequency and intensity of storms in California that they do in the plains, seems like a simple concept. Again, NO ONE is trying to stop wind farms, and they are currently working on improvising.
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See this link for an explanation of the phenomena http://www.crh.noaa.gov/news/display_cms...
Aug 29, 2009 at 11:14 p.m.
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Is that why only happy cows are from there?
Aug 29, 2009 at 9:37 p.m.
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CA does not have many tornadoes that I am aware of.
Aug 29, 2009 at 9:28 p.m.
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It never rains in California.
Aug 29, 2009 at 9:22 p.m.
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Its funny how they never say anything about the huge wind farms in California that have been up and running for years. They dont seam to have any problems out there. I have seen these wind farms in Ca. and I beleive they are a lot bigger than any they have in the states they listed. I agree with onelife2live just anouther excuse to try and stop wind farms.
Aug 29, 2009 at 8:55 p.m.
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Just another exuse for the weatherman/woman to be wrong. :)
Improve the Doppler radars I guess, wind energy is too good to pass up..jmo
Adapt, improvise and overcome the obstacles.
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