MONTGOMERY, Ala. — The National Weather Service is making an effort to issue fewer tornado warnings so the public will pay attention more, according to a meteorologist who deals with weather warnings.
The advance of technology in the past 10 years or so has made predicting severe weather easier, said John De Block, warning coordination meteorologist with the weather service's Birmingham, Ala., office. But the fallout may be complacency.
"There are studies that have some merit that show people become numb to hearing warning after warning," he said. "They hear a warning and nothing happens, so they don't pay attention the next time and the next time."
Weather radar now can show storms with circulation, the major indicator that a tornado may form. Those tornadoes on radar are the source of most warnings now.
"The technology is good," De Block said. "But it hasn't advanced enough yet to show us what's taking place closer to the ground. The radar may show circulation 8,000 feet above Montgomery, but we can't determine what's going on closer to the ground."
On April 7, warnings were issued at 3:01 a.m. CT for Perry and Bibb counties southwest of Birmingham, and 3:13 a.m. for Dallas County west of Montgomery. The storms were part of a powerful weather system that moved through the area spawning severe thunderstorms and torrential rains.
No confirmed touchdowns were associated with the warnings. That's a good thing for the people who live in the area, but in a way it's bad for meteorologists.
Since that date, the Birmingham office, which covers more than half of Alabama's 67 counties, has issued 723 tornado warnings with 320 confirmed tornado touchdowns, De Block said.
That's a detection rate of about 77%, but De Block also calls it a false alarm rate of about 74%. Since Oct. 1, 2007, the average lead time between a tornado warning and touchdown is 16.78 minutes, he said.
"We want the detection rate to be higher than the false alarm rate," De Block said. "Our position is that we would rather have the warning out there if conditions look favorable to tornadic development. We would rather have an informed public.
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