Impact-based severe weather warnings improve response time

This is Mexico's severe weather shelter that can hold over 2000 people and withstand 200 MPH winds for 40 minutes.

April 1st marked the beginning of a region-wide experimental warning test through the National Weather Service.

The impact-based warnings were first tested in two Kansas offices, and all three Missouri forecast offices in 2012. The experimental system now covers 38 across the heartland.

The devastating tornado in Joplin in May 2011 was the deadliest since severe weather record-keeping began in the early 1950s. This showed forecasters the need for an upgrade in their warnings.

Social scientists and meteorologists collaborated to survey the event. They found some glaring issues involving threat reaction time by Joplin residents.

Many survivors said their first source of warning was the outdoor warning system that sounded more than once before the tornado hit. Many residents commented that they thought it was another false alarm, since the siren had sounded in previous warnings and no damage occurred.

Others said they sought a secondary source of confirmation to determine the threat even after the warning was issued. Scientists came to the conclusion that credible risk signals prompt people to take protective action.

Missouri has been experimenting with these warnings since last year, but surrounding states will see additional wording in their warnings from the National Weather Service.

Each warning includes a hazard statement, recommended actions, and a damage threat level.

"I'm a firm believer in that and our messages aren't quite as stern but they are action messages," Audrain County Emergency Manager Steve Shaw said. "What we've decided as a county is we don't send out...through our notification system we don't send out watches. And the reason why we do that is there could be several watches during the day and again how many times is your phone going to ring before you look at the number and go, 'Oh that's that agency, I'm not answering that anymore.' So we only send out warnings and our philosophy is if you get a call from our system, there's an action that is directly related to that, whether it's shelter in place, whether it's evacuate, whether it's get in the know something to that effect."

The goal of this experiment is to motivate people to take action immediately by easily recognizing the urgency and level of risk, as well as the forecaster's confidence in the threat.

This will help emergency managers like Shaw disseminate information much more efficiently and accurately to their county. It will also help broadcast media get critical storm threats and risks out to their viewers as quickly as possible.

For more information and examples of impact-based warnings, you can go to the National Weather Service in St. Louis' website,