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Latest radar faster, sharper

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By Christian McPhate / Staff Writer
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New system enables improved weather predictions in region

The National Weather Service in Fort Worth is using a new series of low-level, high-resolution radars to improve severe-weather predictions such as the downburst of tornadoes before they ravage the metropolitan area, according to Mark Fox, a warning and coordination meterologist with the weather service office.

The new system replaces aged Doppler radar systems and will improve a meteorologist’s ability to predict severe weather — tornadoes and hail storms, for example — sooner and with more precision.

The new radars provide data every 60 seconds, scanning the low-level clouds in a 50-mile radius, compared with the five-minute wait of Doppler radars that meteorologists currently use to predict severe weather.

“It’s a much better indication of the winds,” Fox said, “and you can actually see the circulation.”

There are eight dual-polarization X-band radars planned for the network. Four of them have been installed in Addison, Cleburne, Midlothian and Arlington. One was placed in Denton at the University of North Texas, and another is planned for the Eagle Mountain Lake area.

The Center for Collaborative Adaptive Sensing of the Atmosphere (CASA) and the North Central Texas Council of Governments embarked on a five-year, $10 million project to create the Dallas-Fort Worth Urban Demonstration Network.

Established in 2003, CASA was started as a prestigious National Science Foundation engineering center with more than $40 million in federal, university, industry and state funds, according to CASA’s website.

The CASA program, which interprets the data provided by low-level, high-resolution radars, was developed through a partnership among academia, industry and government dedicated to engineering revolutionary weather-sensing networks.

Researchers from the University of Massachusetts, the University of Oklahoma and Colorado State University were tasked with developing the concept of a low-level, high-resolution radar system.

The reason is simple: Current forecasting and warning systems rely on data provided by the Next-Generation Radar (Nexrad) system, a network of 160 high-resolution Doppler weather radars.

The 25-year-old Doppler network, according to Fox, has a limited ability to scan the lower part of the atmosphere where most severe weather forms because of Earth’s curvature and buildings that obstruct signals.

Amanda Everly, an emergency preparedness technical specialist for the North Central Texas Council of Governments, said the new radar system eliminates a Doppler weakness. When the Doppler radar in south Fort Worth shoots a signal northeast toward Collin County, a gap in detection appears at the edge of Collin County because of the curvature and continues to widen the farther the signal projects.

“So we’re getting [scans] of the upper atmosphere,” she said, “but nothing to predict what was happening in the gap.”

The gap is a critical area that needs monitoring, especially with the various outbreaks of 16 tornadoes that plagued North Texas last year, one of which was an F4 that ripped through the Granbury area, killing six and injuring 100 people.

“They really need to know what’s happening on the ground,” Everly said.


Technology to safety

CASA overcomes the effects of the Earth’s curvature and obstructions such as buildings by implementing a new approach called distributed collaborative adaptive sensing, which refers to the use of several small radars installed on existing rooftops and cellular towers just a few miles apart.

The radars communicate with each other, passing signals back and forth like a technical team, which allows them to adapt their sensing modes to rapidly changing atmospheric conditions and send “up-to-the-second” radar information to the National Weather Service in Fort Worth.

“The idea was to develop a whole new way to do sensoring, [one that] can look close to the ground,” said Brenda Phillips, co-director of the CASA project.

The idea, Phillips said, was developed from practices used by storm chasers who install small radars on their vehicles to detect tornadoes as they’re forming.

Researchers wondered what would happen if they placed small radars on towers to act as a network that relays information and, in turn, shares it with the weather service.

The current Nexrad towers, she said, are spaced 250 miles apart, so the radar beam shoots straight out but the Earth’s curvature causes a gap between the beam and the weather condition that’s developing in the lower part of the atmosphere.

Researchers installed four CASA radars in southwest Oklahoma and monitored them over a four-year period. The radars were successful, so researchers decided to discover how the network of small radars would work in an urban setting.

Juan Ortiz, emergency management coordinator for Tarrant County, requested that they bring it to North Texas.

“The DFW area offers an excellent opportunity to test these types of technology because we are in Tornado Alley,” Ortiz said. “We have a lot of risk.”

Four private-sector companies donated eight radars for the network, according to Everly, but asked if the North Central Texas Council of Governments could come up with the money to operate the radars. Emergency managers in each jurisdiction paid $100,000 for installation. It costs $500,000 to operate the network yearly.

During this year’s spring storm season, only two radars in the network were operational, but they proved valuable.

“We were able to capture a tornado in Dallas that wasn’t warned by the weather service radar,” Phillips said.

Ortiz said the idea is to give people earlier warnings through television, radio and the Internet so they can take safety precautions before hail storms, ice storms or tornadoes strike.

“These [are capabilities] we just dreamed about in 1995 when I first started in the field,” said Ortiz, “and now we’re beginning to see that [CASA radars] will give us longer lead times in order for citizens to be better prepared.”

The North Central Texas Council of Governments wants to eventually implement 16 to 20 radars to cover North Texas.

CHRISTIAN McPHATE can be reached at 940-566-6878 and on Twitter at @writerontheedge.