Monday, February 25, 2008

Image from tornado may lead to precise storm warnings

Terra Daily: An unexpected radar image of airborne debris from the Feb. 6 tornado that killed four people in Lawrence County, Ala., might help scientists develop better tools for warning the public when and where strong tornadoes are on the ground.

Scientists in the Earth System Science Center at The University of Alabama in Huntsville (UAHuntsville) are studying radar data from the early morning tornado to see if the radar signature from the debris is so distinctive that computers can be programmed to instantly recognize it, so more timely and precise warnings might be issued.

"The real advantage would be the precision," said Dr. Walt Petersen, the UAH research scientist leading the radar data analysis. "These events are usually going to be associated with large scale mesocyclones, so tornado warnings would probably already have been issued. But those large scale rotation features can cover several miles.

"With this debris signal, we might be able to pinpoint the precise spot where a tornado is on the ground. It would be great to be able to say, 'The tornado is right there, at that town.' If you could automate a system to do that, it would be quite handy and useful."

…This was the first time a significant tornado has hit within range of the advanced radar unit at the Huntsville International Airport since it was put in service in late 2004. Other storm-related debris sightings using similar radar technology at the National Severe Storms Laboratory in Norman Oklahoma have been rare, so every sighting adds substantially to the paltry information previously available.

…The ability to recognize flying debris wasn't something scientists really expected. "This was totally serendipitous," said Dr. Larry Carey, an ESSC scientist working with Petersen. "Everything else we've done (with ARMOR) were things we pretty much expected. This wasn't really planned. It is just an added benefit of the technology."

If computers can be programmed to recognize debris in the radar data, that programming might be a standard feature when the National Weather Service upgrades its existing nationwide NEXRAD radar network to dual polarimetric capabilities beginning in 2009. While the debris feature might not reduce the number of false tornado warnings, it could add a level of urgency and precision to warnings when tornadoes do occur, Petersen said….

Photo of tornado in Seymour, Texas, 1979, from NOAA, Wikimedia Commons

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