1999 Great Plains tornado outbreak

From May 2–5, 1999, a large, historic, and devastating tornado outbreak took place across much of the Central United States, causing catastrophic impacts. During this three-day event, 141 tornadoes touched down in these areas. The most dramatic events unfolded during the afternoon of May 3 through the early morning hours of May 4 when more than half of these storms occurred. Oklahoma experienced its largest tornado outbreak on record from this event, with 70 confirmed, in what is referred to as the May 3 outbreak, or more officially by the National Weather Service (NWS) and NOAA as the Great Plains Tornado Outbreak of May 3–4, 1999, or the Oklahoma/Kansas tornado outbreak. The most notable of these was the F5 Bridge Creek–Moore tornado which devastated Oklahoma City and suburban communities. The tornado killed 36 people and injured 583 others; losses amounted to $1 billion, making it the first billion-dollar tornado in history. Overall, 50 people lost their lives during the outbreak and damage amounted to $1.4 billion.

On May 2, a strong area of low pressure moved out of the Rocky Mountains and into the High Plains, producing scattered severe weather and ten tornadoes in Nebraska. The following day, atmospheric conditions across Oklahoma became significantly more favorable for an outbreak of severe weather. Wind profiles across the region strongly favored tornadic activity, with the Storm Prediction Center stating, "it became more obvious something major was looming" by the afternoon.