By Jim Forsyth
(Reuters) - The National Weather Service on Monday plans to begin a new initiative in Kansas and Missouri designed to make people in Tornado Alley sit up and take notice when potentially devastating twisters are headed their way. Under the new system, tornado warnings will be accompanied by stark language like, "mass devastation is highly likely, making the area unrecognizable to survivors," according to the National Weather Service.
Or even: "This storm is not survivable." "We call this 'impact-based warning," Dan Hawblitzel, a National Weather Service meteorologist in Pleasant Hill, Missouri, said on Sunday.
"The idea is to better convey the impact that a storm is likely to have on a community." Current National Weather Service tornado warnings generally cover portions of counties and urge people in the storm's path to take action. "There is quite a lot of over-warning going on; it's kind of the car-alarm syndrome," said Col Galyean, a meteorologist with The Weather Channel.
"People who live in areas where tornadoes happen frequently, like Joplin, Missouri, for example, are kind of becoming desensitized to the warnings." A tornado slammed into Joplin last May, killing 161 people in the southwestern Missouri city and causing extensive damage. The new warnings will be tested in the two states through November 30. After that, a panel of social scientists and meteorologists will examine the responses and determine whether the system should be used nationwide, Hawblitzel said.
Messages such as, "Complete destruction of entire neighborhoods is likely" may get more people posting on social networking sites and taking instant action, Hawblitzel said.
Galyean and Hawblitzel say the more detailed warnings are largely made possible because of a new type of Doppler radar called dual polarization, which can measure both the horizontal and vertical properties of a storm system and can tell forecasters whether debris is being picked up by the storm, a sure sign of a destructive system.
"Right now it's tough to tell if a storm is actually causing damage," Galyean said. "This technology allows forecasters to actually see inside the storm, and see different parts of the same storm system, to better analyze its speed, direction, and destructive potential."
"This way we can be more sure that a tornado is heading straight for a heavily populated area," Hawblitzel said.
The warnings will go out to radio and television broadcasters who issue emergency warnings, to local emergency management personnel who activate sirens and dispatch emergency services, and to listeners of National Weather Service radio.
In the San Antonio area last month, many people who were caught in the path of a damaging flurry of tornadoes said they had heard the warnings, but that it was the sight of a tornado that prompted them to take action. "Forecasters do worry about that," Galyean said. "We can get the information to the public, but the key is to get the public to pay attention."
(Editing By Corrie MacLaggan and David Bailey)