Black and white image of radar echoes from the NSSL 10 cm Doppler radar in Norman at 2340Z, April 10, 1979. Credit: NSSL

Photo of a TV screen showing the radar reflectivity display of the approaching Wichita Falls supercell. Time is approximate 2330-2340Z, April 10, 1979. Credit: © Doug Peterson

Map of Radar Reflectivity and Mesocyclone Positions of the Wichita Falls, Texas Supercell at 2330Z, April 10, 1979. Credit: Don Burgess, OSF

Map of Radar Reflectivity and Mesocyclone Positions of the Wichita Falls, Texas Supercell at 0000Z, April 11, 1979. Credit: Don Burgess, OSF

Color image of radar reflectivity values from the NSSL 10 cm Doppler radar in Norman at 2155Z, April 10, 1979. Credit: NSSL

Color image of radar velocity values from the NSSL 10 cm Doppler radar in Norman at 2155Z, April 10, 1979. Note: warm colors indicate outbound velocities and cool colors indicate inbound velocities. Credit: NSSL

Color image of radar reflectivity values from the NSSL 10 cm Doppler radar in Norman at 2209Z, April 10, 1979. Credit: NSSL

Color image of radar velocity values from the NSSL 10 cm Doppler radar in Norman at 2209Z, April 10, 1979. Credit: NSSL

Color image of radar reflectivity values from the NSSL 10 cm Doppler radar in Norman at 2216Z, April 10, 1979. Credit: NSSL

Color image of radar velocity values from the NSSL 10 cm Doppler radar in Norman at 2216Z, April 10, 1979. Credit: NSSL

Color image of radar reflectivity values from the NSSL 10 cm Doppler radar in Norman at 2309Z, April 10, 1979. Credit: NSSL

Color image of radar velocity values from the NSSL 10 cm Doppler radar in Norman at 2309Z, April 10, 1979. Credit: NSSL

Color image of radar reflectivity values from the NSSL 10 cm Doppler radar in Norman at 2322Z, April 10, 1979. Credit: NSSL

Color image of radar velocity values from the NSSL 10 cm Doppler radar in Norman at 2322Z, April 10, 1979. Credit: NSSL