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.
March 1913 tornado outbreak sequence
March 23, Easter Sunday, was the most violent tornado outbreak to affect the northern Great Plains on so early a date in the year—a record that still stands as of 2012. That day, four F4 tornadoes affected portions of eastern Nebraska and western Iowa, killing at least 168 people. The deadliest tornado of the day was a potent F4 tornado that grew to in width as it passed through northern Omaha, Nebraska, killing at least 94 people in the city proper and three in rural areas. Damage in Omaha reached at least F4, possibly even F5, intensity, though confirmation of F5 damage could not be determined from available evidence. The tornado is the 13th deadliest ever to affect the United States and the deadliest to hit the U.S. state of Nebraska as of 2014. No other violent tornado would affect Omaha for another 62 years. Outside the Great Plains, the outbreak of March 23 also produced two other F4 tornadoes, one each in Missouri and Indiana, including a devastating path more than through southern Terre Haute, Indiana, killing 21 people and injuring 250.