Oklahoma Climatological Survey
The Deadly Oklahoma Tornado Outbreak of May 3-4, 1999
Event Summary 
On the afternoon of May 3, 1999, thunderstorms formed in southwest Oklahoma ahead of the dryline. The thunderstorms quickly grew to severe limits as they were located in an area of large surface instability and were aided by an upper level disturbance approaching from the west.

One of the more significant tornado outbreaks in Oklahoma history resulted as these storms formed in an area identified as having a high risk of severe weather.

  • To gain an understanding of precursor surface conditions that can lead to an outbreak of severe weather.
  • To properly interpret WSR-88D data to find mesocyclones in velocity products.
  • To properly interpret WSR-88D data by noting that severe weather signatures are range dependent.
  • To be aware that multiple weather hazards can occur simultaneously.
Convective Outlook 
Storm-Relative Velocity 
Workshop Version : Event Exercise
Self Study Version: Event Exercise
Reference Material 
The Central Oklahoma Tornado Outbreak of May 3, 1999 From NWSFO in Norman 
Thunderstorms and Tornadoes
OK-FIRST Project, Oklahoma Climatological Survey, 100 East Boyd, Suite 1210, Norman, OK 73019
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