High-Speed Storm Radars to Track Tornadoes, Fend Off Tragedy

When tornadoes start killing Boy Scouts, the world pays attention. But even as a deadly EF-4 tornado whipped through Little Sioux, Iowa, with 145-mph-plus winds last Wednesday night, federal climate scientists and a group of university researchers were in the early phases of testing high-tech replacements for an aging Doppler radar system. Twisters across the United States in 2008 are headed for a record-setting pace (February's 148 nearly doubled a 37-year-old record); however, by 2013 a new network of satellites could be triangulating microfrequencies from the sky to Wi-Fi for real-time reactions to dangerously shape-shifting weather patterns.

America's current system for detecting tornadoes—about 120 Next Generation Radar, or NEXRAD, devices tracking a storm's direction and velocity—has been the backbone of weather prediction since the early 1990s, but experts say it is deeply flawed. The radars are tilted upward from the Earth half a degree, which may not seem like much—until you factor in the curvature of the Earth. By the time you get 40 or 50 miles out, radar beams are more than one-half mile high, therefore missing the bottom third of the troposphere where severe weather often begins to form. And at 5 to 6 minutes for a complete area scan, NEXRAD simply remains too slow.

The Collaborative Adaptive Sensing of the Atmosphere (CASA) network aims to address both problems, with short-range-satellites targeting the bottom of a storm and refreshing much more often—as in every minute. "CASA radars are gap-filling radars," explains Harold Brooks, a research meteorolgist at the National Oceanic and Atmospheric Administration (NOAA), which is developing the system with four schools across the country. "While the main NEXRAD radars give a really good view of the storm aloft, CASA radars could be set up to probe that area where the NEXRAD radars don't see."

This new rig borrows technology from the U.S. Navy, which for years has been using a similar system to track vessels on the seas. CASA radars, however, will be installed just a few miles away from each other on rooftops, cell towers and other existing infrastructure. The first testbed is a network of four nodes in the middle of Tornado Alley in southwestern Oklahoma; other early sites include Houston and Mayaguez, Puerto Rico. CASA officials expects to see at least quasi-operational CASA networks within the next five years to address some well-known gaps in the NEXRAD system, and widespread deployment within the next 15 years.

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