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Weather warnings refined

Alerts will focus on individual areas instead of counties starting Oct. 1.

BIRMINGHAM, Ala. - The National Weather Service is revamping the way it has issued severe weather warnings for decades with a new system designed to mark a geographic bull's-eye where a storm will hit.

The system, which goes into effect Oct. 1, switches from alerts based on county lines to notices aimed at specific communities, weather service officials said Tuesday. Using radar and computer modeling programs, the system is meant to predict the moment a storm will hit a community or even a certain crossroads.

Known as storm-based warnings, the new alerts could reduce a warning area from thousands of square miles to a few hundred square miles, experts said.

"A storm-based warning focuses on a storm itself and the geographic area that might be affected by it," said Eli Jacks, a meteorologist at weather service headquarters in suburban Washington. "We can really reduce the number of people being warned by reducing that geographic area."

The new system will initially be limited to warnings for tornadoes, severe thunderstorms, floods and marine hazards. Later, it will be expanded to include other threats like extreme heat, Jacks said.

Tornado forecasting began in the late 1940s, and the government started issuing weather warnings in the 1950s based on a network of storm spotters with radios and telephones.

Officials say the new system will make it easier to send weather warnings through cell phones and other handheld devices.

Some weather experts are concerned that radar has its limits and that a fast-moving storm can change direction, suddenly taking aim at an area not mentioned in the storm warning. But Jacks said the system will be able to keep up with abrupt changes.

A report by the National Oceanic and Atmospheric Administration predicted the system would save $100-million annually, mainly by cutting back on unneeded business closings.

The new warnings have worked well during trials in Indiana, said Dave Tucek, who coordinates severe weather warning in the agency's Indianapolis office.

"I think it has been a good system," said Tucek. "The idea behind it ... is that there is no reason to warn the northern end of a county about something that is in the southern end of a county."

[Last modified September 19, 2007, 01:29:15]