Tornadoes tear through Southern states, but new alerts saved lives
The Super Tuesday tornadoes were the deadliest in the US in more than a decade.
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The outbreak was triggered by the mix of a very powerful winter storm system moving across the central US – not unusual for his time of year – and an unseasonably warm, moist, and unstable air mass over the Mississippi Valley in its path, says Greg Carbin, a meteorologist at the Storm Prediction Center. "When you look at these conditions, they are clearly one or two months ahead of schedule" compared with a typical year, he says.Skip to next paragraph
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Forecasters at the Storm Prediction Center got their first inkling that Tuesday had the potential be a violent weather day some six days before as they looked at the results from their medium-range forecasting model. As the storm system tracked across the country, the potential grew. By the time the system was 12 to 18 hours west of the stricken region, they had started to issue maps to local forecast offices identifying the regions with the highest likelihood of experiencing severe weather capable of spawning tornadoes.
"People were very well-warned," says Laura McPherson, spokeswoman for Tennessee Emergency Management. "We had very warm temperatures the day before and for the past few days meteorologists have been warning that storms were very, very likely."
One challenge for local forecasters who issued specific tornado warnings – and for residents who had to respond to them – was the speed with which the violent, potentially tornadic thunderstorms were traveling. If a storm moves at a somewhat sluggish 20 miles an hour and forecasters get spotter reports of a funnel cloud or see its telltale signature on their radar while it's still 10 miles out, they can post a warning that gives people a 30-minute heads up. But if a storm roars along at 60 miles an hour, that leaves 10 minutes between a warning and the storm's arrival.
For this system, surface winds were cranking along at between 50 and 70 miles an hour, with far higher speeds aloft. Preliminary estimates suggest these winds pushed individual storm cells along the front at from 35 to up to 70 miles an hour, Mr. Carbin says. And any small error in estimates of a storm's track can rapidly multiply, adding an additional challenge to issuing tornado warnings to the right place at the right time.
The federal government doesn't map siren coverage in the US, and private siren manufacturers don't give out specific sales information. But they do acknowledge that the use of siren systems, often accompanied by cellphone or e-mail warning systems, is growing throughout the US.
Urban areas tend to be well covered by sirens. It's more difficult for rural areas to raise tax money to purchase them, especially since more are needed to cover vast areas, says David Freeman, the emergency management director of Pope County, which includes Atkins.
Atkins received six used sirens for free last spring when Entergy Arkansas upgraded the warning system at a local nuclear plant. "I've talked to a lot of residents who credit those sirens for saving lives," says Mr. Freeman.
Professor Aguirre says what's lacking most is practical experience from storm survivors. He points to one of the most controversial items: Whether those in the path of a storm should try to escape in a car. Some experts warn against it; others say it needs to be explored.
"We have no way ... to ask people systematically what they did in their own microenvironment to protect themselves," says Aguirre. "We don't have any kind of sustained research effort to prove what strategies seem to work and which don't."
In Atkins, a new church and dozens of homes were destroyed. But many people told Austin, the barber, that they felt well informed about the looming front.
"They're pretty good about sounding the sirens," he says. "We're real thankful."