Emergency communication system
161 people were killed and at least 990 injured when an EF5 multiple-vortex tornado hit Joplin, Missouri. Because Joplin is located in a tornado-heavy area of the country, many people considered the tornado sirens routine and ignored them. Instead, many residents waited until they received confirmation from another, non-routine, source, such as seeing the tornado, a radio or TV report, or hearing a second siren. In the aftermath, an assessment team recommended that emergency warnings take risk perception into account to convey a sense of urgency. NOAA Officials are considering ways to change the warning system to distinguish smaller tornadoes from more deadly ones.
Tornadoes of 2009
Another major severe weather event developed early on May 8 over southwestern Kansas. It quickly formed into a major progressive derecho which tracked across the central Plains, the Ozarks and into the Ohio Valley. The city of Joplin, Missouri had a derecho. It eventually became an F1 tornado destroying a TV station tower. Several tornadoes also developed, primarily in the Springfield, Missouri area where damage was reported. A moderate risk of severe weather was issued primarily due to the wind threat. Two people were killed near Poplar Bluff, Missouri when winds knocked a tree onto their car. Another Missouri resident suffered a fatal heart attack after he was blown away 
from his home and dropped into a field by an EF2 tornado. A woman was killed in southeastern Kansas after her mobile home was blown off its foundation. Two other deaths occurred in Kirksville, Kentucky from an EF3 tornado. Eventually, the storm developed a tropical cyclone-like structure, with a well-defined eye feature. In addition, winds were measured as high as in Carbondale, Illinois.