(CBS/AP) KANSAS CITY, Mo. - Even expert storm chases would have struggled to decipher the difference between the tornado warnings sent last May before severe weather hit Joplin and, a few days later, headed again toward downtown Kansas City.
The first tornado was a massive EF-5 twister that killed 161 people as it wiped out a huge chunk of the southwest Missouri community. The second storm caused only minor damage when two weak tornadoes struck in the Kansas City suburbs.
In both cases, the warnings were harbingers of touchdowns. But three out of every four times the National Weather Service issues a formal tornado warning, there isn't one. The result is a "cry wolf" phenomenon that's dulled the effectiveness of tornado warnings, and one the weather service hopes to solve with what amounts to a scare tactic.
In a test that starts Monday, five weather service offices in Kansas and Missouri will use words such as "mass devastation," "unsurvivable" and "catastrophic" in a new kind of warning that's based on the severity of a storm's expected impact. The goal is to more effectively communicate the dangers of an approaching storm so people understand the risks they're about to face.
"We'd like to think that as soon as we say there is a tornado warning, everyone would run to the basement," said Ken Harding, a weather service official in Kansas City. "That's not how it is. They will channel flip, look out the window or call neighbors. A lot of times people don't react until they see it."
The system being tested will create two tiers of warnings for thunderstorms and three tiers for tornadoes, each based on severity. A research team in North Carolina will analyze the results of the experiment, which runs through late fall, and help the weather service decide whether to expand the new warnings to other parts of the country.
Laura Myers, a social science research professor at Mississippi State University, said people she has interviewed want more advance warning about a potential tornado strike and more information on the specific locations where the storms are expected to hit.
"We have found in Mississippi and Alabama and various other Southern states that people feel they would constantly be going to a shelter if they heeded every tornado warning," she said. "For people in mobile homes, that's the craziest thing.
"To get to a shelter, they have to leave home," she said.
"They feel like if they left during every watch or warning, they would be on the road all the time."
The primary audiences for weather service's written bulletins are broadcasters who issue warnings on the air and emergency management agencies that activate sirens and respond to the storm's aftermath. In the event of a Joplin-like tornado, the new-look warning would have an urgency hard to ignore.
Andy Bailey, a meteorologist with the National Weather Service office in Pleasant Hill, Mo., said it might look something like this: "THIS IS AN EXTREMELY DANGEROUS TORNADO WITH COMPLETE DEVASTATION LIKELY. ... SEEK SHELTER NOW! ... MOBILE HOMES AND OUTBUILDINGS WILL OFFER NO SHELTER FROM THIS TORNADO - ABANDON THEM IMMEDIATELY."
Had such a warning come across his television set on May 22, Joplin resident Jeff Lehr said he might have sought shelter.
Instead, it wasn't until a siren distracted him from a sporting event he was watching on TV that he looked out a window and saw what appeared to be dark thunderstorm clouds.
Even then, he didn't take cover until the windows began imploding in his apartment.
"After hundreds of times of similar thunderstorms approaching Joplin, many of those with tornado warnings attached, and you see them pass ... after all those storms, you kind of get jaundiced about the warnings and tend not to give them the weight you probably should give them," said Lehr, a reporter at The Joplin Globe.
When asked if the strong language to be employed in this test could, itself, add to the "cry wolf" phenomenon, Myers conceded that that is a risk, but said that the language will only be used in limited circumstances.
"This language is only going to be used when there's a high probability" of a serious storm occurring, she told CBS News, or when tornadoes have already been confirmed by storm watchers or radar.
James Spann, chief meteorologist with WBMA-TV in Birmingham, Ala., said the impact-based warning experiment could provide broadcasters and emergency management agencies with a useful tool in an age when a majority of people still wait for an outdated technology - tornado sirens - to seek shelter.
He blames the siren mentality and high number of false alarms for the complacency of people living in tornado-prone areas such as Alabama, where 252 people were killed last April 27 in a tornado outbreak that struck communities across the South.
"A lot of politicians and people who don't understand tornadoes try to jump into this," Spann said. "Their first reaction is, `We've got to get more sirens.' What are these people thinking? They clearly do not understand the issue."