As tornado season begins the National Weather Service has expanded a pilot tornado warning system to encompass the service's entire Central Region.
After receiving positive reviews last year in Kansas and Missouri, the system has expanded from five to 38 NWS offices in 12 additional states as of April 1.
The project, called Impact Based Warning, is designed to relay more information to the media and residents while making it manageable and easy to understand by improving upon the existing tornado warning system with a heightened focus on word choice and message placement.
"This project was born out of the recognition that language matters, and how we convey risk can mean the difference between life and death during a weather emergency," said John Ogren, acting director of the National Weather Service's Central Region in a statement. "This is one of many efforts we've undertaken since the destructive 2011 tornado season to improve our service to America. One important lesson we learned from 2011 is that standard one-size-fits-all tornado warnings contribute to public complacency."
The enhanced system gives forecasters a three-tiered warning system. Tier one, the most common type of warning will give a bulleted list that clearly communicates hazards.
Tier two is utilized when there is substantial evidence of a large tornado. The warning will include the phrase "This is a particularly dangerous situation," to identify a high threat level. Embedded in the warning will be a damage threat tag of "considerable."
When a violent tornado is likely to produce devastating damage tier three is evoked.. The warning will announce "Tornado Emergency," and direct the public to immediately seek shelter. A damage threat tag of "catastrophic" will be embedded in the warning. This is the highest level of tornado warning and will only be used in rare cases, such as the deadly EF-5 tornado that struck Joplin, Mo. in 2011.