KANSAS CITY, Mo. —Many Joplin residents either ignored or were slow to react to the first warning sirens about a massive and deadly tornado this spring, partially because of years of false alarms, the government said Tuesday.
The National Oceanic and Atmospheric Administration said many people waited for additional information like seeing the tornado or a television or radio report about the urgency of the threat.
The storm killed 162 people.
The report said later warnings weren't worded strongly enough.
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"Once there became an awareness that something big was going on, we wanted the severe weather statements and warnings to project a heightened sense of urgency," said Richard Wagenmaker, a National Weather Service meteorologist in Detroit and leader of the assessment team.
The warnings should have said "something along the lines of 'This is a very large and dangerous tornado and don't mess around,' basically," he said.
Instead, they were the "basic template," he said.
The report found that most Joplin residents didn't respond to the first siren because of an apparent widespread disregard for tornado sirens.
"The majority of surveyed Joplin residents did not immediately go to shelter upon hearing the initial warning," the report said, adding that those people "did not take protective action until processing additional credible confirmation of the threat and its magnitude from a non-routine, extraordinary risk trigger."
Wagenmaker said it was unclear if the slow public response cost lives.
"It's really hard to tell how many people that perished in the tornado did not take shelter," he said during a conference call. "It was a very large tornado, so there were certainly a number of people who did all the right things, took shelter in the best available place, but still found themselves in situations that weren't survivable. So it's really hard to make that assessment."
The report said the weather service was considering developing other forms of notifications, including GPS-based communications involving text messages, smart phone apps and upgrades to the Emergency Alert System and NOAA Weather Radio.
NOAA also said the agency wanted more collaboration between what it calls the "weather enterprise," which includes the weather service, media and emergency management, in order to make warning systems consistently better at conveying the seriousness of a threat.
Keith Stammer, Jasper County emergency manager, said the city has applied for federal funding for 10,000 weather radios for Joplin households and for 4,000 in-place shelters for Joplin residents.
The Weather Service team interviewed about 100 people, including residents, emergency responders and city officials, and also examined warning and forecast services before the powerful tornado cut through the city of about 50,000 and reduced much of its southern half to ruins.
Several people interviewed said they would like to see different siren tones for varying levels of emergencies, the report said.
Lynn Maximuk, director of the National Weather Service's central region, pointed out that the siren systems are run by emergency management departments.
"We're trying to improve our services from the weather service and how we communicate the threat information to better serve the other parts of the weather enterprise ... to try to help them develop a better way to make our nation weather-ready," Maximuk said.