Tornado outbreak of May 4–6, 2007

From May 4–6, 2007, a major and damaging tornado outbreak significantly affected portions of the Central United States, with several strong to violent long-track tornadoes occurring across much of the impacted regions. The Storm Prediction Center (SPC) issued a moderate risk of severe thunderstorms for May 4 over portions of Central Nebraska, Western Kansas, Western Oklahoma, Eastern Colorado and portions of the Texas Panhandle. The most destructive tornado in the outbreak occurred on the evening of May 4 in western Kansas, where about 95% of the city of Greensburg in Kiowa County was destroyed by an EF5 tornado, the first of the new Enhanced Fujita Scale and such intensity since the 1999 Bridge Creek–Moore tornado. The supercell killed 13 people, including 11 in Greensburg and two from separate tornadoes. At least 63 people were injured in Greensburg alone. It was the strongest tornado of an outbreak which included several other tornadoes reported across Oklahoma, Colorado, Kansas and South Dakota that occurred on the same night.

On the morning of May 5, the SPC issued a high risk across central Kansas and Nebraska. The Storm Prediction Center also issued a moderate risk for southern South Dakota and northwest Oklahoma and a slight risk for most of Oklahoma, northern South Dakota, southern North Dakota, eastern Nebraska, western Iowa and northeastern Colorado. Severe weather reports were already coming in by late morning, and the first tornado reports came in during the early afternoon hours. The most intense activity took place during the late afternoon and evening hours as supercells developed along a long line from South Dakota to North Texas. Over 80 tornadoes were confirmed that day, along with hail as large as softballs and straight–line winds as strong as 90 mph (145 km/h). The activity weakened in the late evening, but not before the last tornadoes were reported in Iowa in the overnight hours. The SPC also issued a moderate risk for severe storms over parts of central Kansas and northern Oklahoma on May 6. The activity was far less than on the two previous days, however there were still several additional tornadoes across the Plains, all of which were weak. 14 fatalities and 89 injuries occurred as a result of the tornadoes, nearly all of which came from the Greensburg tornado on May 4.

A total of 132 tornadoes touched down during the two-day outbreak, making it one of the largest to occur in the United States. In 2023, tornado expert Thomas P. Grazulis published the outbreak intensity score (OIS) as a way to rank outbreaks. The outbreak received 70 OIS points, ranking it as a major tornado outbreak.